Zaphod,

I wonder if the "feel" of the longer top tube derives from what must be a longer wheelbase that goes with that longer top tube. Long tube/short stem or short tube/long stem, either would let you stretch out your torso. One, however, would have the fronbt wheel a lot closer to the rear wheel than the other (all other things being equal).

On top of that, it may be that frames with long top tubes are generically designed with shallower angles, longer stays, etc, hence, they have a certain "feel" to them.