There are two fairly well established integrated shifting designs available for drop-bar bicycles. One is "Shimano Total Integration" or STI for short and the other is Campagnolo's "ErgoPower" as in Ergonomically-designed system.
Thus, anyone who says they have tried integrated shifting and found it lacking -- most routinely with regard to front derailleur shifting and trimming -- implies that only one of the two integrated shifting systems has been tried. This is because, of these two systems, only the Campy Ergo shifters replicate a barend or downtube shifter's ability to "trim" a front derailleur. In fact, Ergos provide up to 10 different detent positions on the current 9/10 speed front derailleur's shifter. For practical purposes, a two-ring set up will only use 5 of the 10 positions and triples will use 7 of the 10 positions. However, it's safe to say, you can easily "trim" the front derailleur on a tandem fitted with Ergo levers. Moreover, you can sweep through up to five of these positions with a single, full sweep of the up-shift lever (which does not pull double-duty as a brake lever) or a full push down with your thumb on the down-shift paddle. If for no other reason, this one aspect of the Ergo levers make them the ideal system for tandems and their notoriously sub-optimum chainlines.
IMHO, anyone who rides a tandem that has trouble with STI and front shifting or who has opted not to try "integrated shifting" because of the often times cited problems with front derailleur shifting, trimming, and reliability should make a point of test riding a tandem fitted with Ergo shifters at some point in their life. You may not like them, but at least you'll have had a chance to use a system that is better suited to the demands placed on shifters by the inherent, sub-optimum chainlines that 140mm - 160mm rear spaced tandems must deal with.
Bottom Line: If you haven't taken an extended test ride on a tandem with a properly configured Campy Ergo system then you haven't really given integrated shifting a fair chance. STI is only one solution and, IMHO, it's not the best one for a tandem UNLESS the captain is fully committed to STI on personal bikes that are ridden as much or more often than the tandem.
Personal anecdote: I reluctantly gave up downtube shifters in 1991 when I replaced by Raleigh Prestige as my primary ride with an STI-equipped Trek 2300. I used STI exclusively until we purchased our first tandem; a 1996 Santana Arriva. I had no desire to give up my STI levers but was told that Shimano did not yet have an OEM STI solution for triple chainrings. However, if I was willing to spend the money, I could upgrade our Arriva with a pair of Sachs Ergo levers: basically Campy Chorus Ergo levers with a Shimano 8 speed shift disc. To this day, that change was the best component upgrade that I ever made as a cyclist. We now have five road bikes in our stable and all five are fitted with Campy Ergo shifters. They may not be perfect and they're certainly not for everyone, but everyone who rides a tandem should give them a fair try before assuming that they're not a viable option.
NOTE: I have not stock in Campy nor any other personal gain motive for suggesting the use of Ergo shifters beyond a firm belief that a lot of tandem teams who haven't tried them might be surprised to find out how well they work on tandems. I still subscribe to the "find and use what's best for you" but I sense that too many teams haven't had enough exposure to this excellent design for a variety of reasons, some valid and some not.
I have smaller than average hands which is perhaps one of the reasons I immediately took a strong liking to the Ergo design. I have not taken any measurements on the actual lever reach; however, the following are my observations on why certain Ergo features are appealing to me:
1. The brake hood incorporates a more pronounced and ergonomically contoured hood bump that is reminiscent of the pre-integrated aero brake levers such as the DiaCompe 287 and Shimano's Aero levers which I believe had a shorter reach than Campy's pre-Ergopower levers.
2. Similar to the aero brake levers, both the brake and shifter cables are routed out of view under the handlebar tape, leaving the area in front of the handlebars and between the brakes clear of any cable housing.
3. The brake levers are only used for braking and can only move forward and backward which allow them to be gripped when standing to climb or sprint.
4. The design of the hood bump and brake levers provide excellent leverage when applying the brakes while riding on the tops of the brake hoods.
5. Up-Shifting to the larger cogs and chain rings is performed by pushing inward on dedicated shift levers that sit behind the brake lever and fall in line with your index and middle fingers while your hands are either on top of the brake hoods or in the front of the drops.
6. Down-Shifting to smaller cogs and chain rings is performed by pushing down on dedicated thumb paddles that sit on the inside of the brake hood body and fall in line with the natural movement of your thumb while your hands are either on top of the brake hoods or in the front of the drops(although, this takes some practice).
7. Both the shift lever and thumb paddles allow you to shift through a wide range of chain positions / gears in a single movement.
8. As new levers "break-in" and become less stiff, the little or ring fingers can be used to shift the rear-derailleur into a higher gear one cog at a time while riding on the tops of the handlebars by pushing-down on the thumb paddles.
9. Ergo levers can be rebuilt, which is a double-edged sword in that they all "need" to have their right hand shifters rebuilt somewhere between 10 - 15k miles of use.
10. Ergo levers CAN be integrated with Shimano's rear derailleurs and cassettes in one of several different ways. Thus, you can have the best of both worlds.
The downside of Ergo is finding a tandem to test ride that has it,having to make assumptions about how it will shift once it breaks-in given how stiff and notchy a new set of levers feel, the higher cost,and the need for most teams to use a combination of Shimano & Campy components to obtain the often desired gear range.
This is not to say that STI doesn't have its strong suits.
1. The don't need to break-in before they operate smoothly, whereas Campy's levers all start out being very stiff and notchy and don't become smooth until somewhere around 500 - 1,000 mi of use, depending on how often you shift while riding.
2. The brake hood and brake lever fit the contour of most medium and large-size hands better than Ergo's while standing and sprinting or climbing out of the saddle. Ergo's all you to either wrap your hands around the brake hood body or the brake lever, but neither are as"comfy" as the STI's shape.
3. When reasonably maintained and not used aggressively, STI levers seem to keep going, and going, and going, and going without any perceived change in smoothness or reliability.
4. An all-Shimano drive train works incredibly well once adjusted properly; getting them set-up right for a tandem takes a little bit of tweaking.
5. Shimano's components have traditionally been less expensive than Campagnolo's and nearly every bike shop that sells road bikes has replacement parts and can service the full line of Shimano components. However, for a variety of reasons, cost is no longer a major difference.
Again, the most compelling reason to use STI on a tandem is if you exclusively use STI on a personal bike that you ride as much or more often than the tandem. As someone once noted, going back and forth between STI and Ergopower shifting can be about as mentally taxing as switching between driving from the right in the US to the left in the UK.