Interesting thread, since I was thinking about this tonight when riding on my trainer.
I have a road bike, feel very comfortable on it, never any pain, ride and pedal smooth. In the drops my legs have just enough room below my chest to be borderline on the uncomfortable side, but never crossing the line (had my seat be a fraction lower I might be too compact or bunched up).
I thought about what the feel would be like if I added tri bars, since I never rode a bike with one or in that position. I rested elbows and forearms on the top off my handlebars in the middle, stretched my arms out as if I had tri bars, while lowering my back a bit to get into position while I kept pedaling. What I noticed was that in this position my legs were too close to my chest and my pedaling was uncomfortable and inefficient.....I couldnt keep a smooth stroke. Knowing that I only need a few mm more height to my saddle I raised it slightly until I was pedaling in circles again.
Once I felt this comfort zone (and this was a very small adjustment) I went back to the basic road position (bars, hoods, drops), and seemed to like it a bit more with the adjustment.
Is this something that should be considered when doing a road bike fit, basically being perfectly comfortable in all positions, including if you slapped tri bars on the bike?
I never thought of things this way, and not sure why it wouldnt make sense. I know that time trial positions usually have a saddle more forward to work different muscle groups, but the seat height and reach to the area where the bars are should be somewhat consistent, given the fact that the 4 positions (bars, hoods, drops, tri bars) really have more to do with how aerodynamic you are trying to get yourself.