That was an excellent explaination TandemGeek. I too am of the long rear top tube school as I think it has many benefits. I often use the same forumula that was given to me by a once builder of R&E cycles in Seattle.

So one of the design elements of my current tandems is to make a long rear compartment and then use the integrated adjustable stoker handlebar that allows a wide range of stokers to fit easily and still obtain a true custom fit back there.

http://www.bohemianbicycles.com/Imag...62de06c1_b.jpg

You are correct that some stokers may not need such length and space back there, but I see few downsides and it opens up the possibility of riding with other stokers. I have already had a lot of fun taking various friends on the tandem. I took my girlfriend one day which was a great fun ride of 15mph and the next day a very fit friend of mine and it was like having a V8 in the back.