It has been many years since I rode a tubular, but from memory it seems that the best, modern, clinchers provide all or most all of the handling, comfort and speed of classic sew-ups. I really would not consider an automatic car, because I find that driving them deprives me of much of the "feel" and feedback that a manual provides. This is not the case with clinchers. Other than the pain in the a** which tubulars provide, the riding experience is not really improved with them over good clinchers. When downtime, stretching, gluing, drying, seasoning, aging, praying, hunting down tubulars and fixing them is taken into consideration, it is no wonder that even the most die-hard classical devotee, finds himself going for the convenience and security of clinchers.
As to the issue of using smaller toptube frames as one grows older... I also beg to differ. I am proud to be 51 years old. I am also proud that even though I was a bit of flexibility freak as a youngin, I am still more flexible in some ways now, and these are the ways that make stretching out on a bike easier now, thus justifying a longer stem and top tube than I used in my teens. I was a professional ballet dancer all during the 70's and now with the benefit of long serious yoga sessions, I have more forward bend in my 50's. Of course, I am less explosive and powerful, but with my wife's help (also yoga practitioner and sometimes teacher), I do have more critical flex-ability. My abdomen and spine reach down past my thighs when I do a foward bend and I was far from that even 5 years ago. (Without any growth in the girth of the mid section- Ho ho ho, I heard those comments coming).
Garth Libre hopefully inspiring others to stretch and breathe here on the list and in Miami Fl.