hi there - On the wheel pref, I can't say I notice any difference really. Tyre choice and frames influence ride quality far more than wheel size. The Rose has 700*35's and my Thorn RST has 26*1.6 both are schwalbe marathon supremes. The Thorn is a slower and much more comfortable ride. I think 700's "look better" for what its worth. 700's give a better choice of fast race tyres, but for touring / commuting 700 and 26 have the same choices.
On the tandems, I traded our old triplet (Me n'u2) for the raven twin to use with the boys. We still had our old discovery tandem, which although cosmetically is a bit shabby, its a better fit for my wife and I, and its this bike I have hopes to use more this year to rekindle our tandem mojo. The shabiness of it and the amount of riding we actually do on it this year will determine whether I send that off for a BJ respray next. (and the finances of course)
Incidentally, how often have you found you use the S&S couplers ? I spec'd them on the raven twin, but have used them loads LESS than I imagined. Its a really nice feature but if we're en-famille the bikes are on the roof. Its only if I went with 1 son to a remote ride and then I'd put it inside the car. Prob used less than 10 times