Road bikes are generally available in what I'll (somewhat arbitrarily) break into two "categories:"
"Vintage" bikes with steel or aluminum frames and 27" wheels
"Modern" bikes with composite or carbon frames and 700c wheels
Assuming equivalent cost for both (yes, I know it is a radical assumption, but accept it for the course of this discussion), please enlighten me as to the relative merits/demerits of each option.
As I see it currently, advantages of the vintage bike include a potentially longer life for the frame, more relaxed frame geometry giving a softer ride and less-twitchy handling, more durable wheels (many of the vintage bikes had steel rims), generally higher spoke-count wheels, less dish to the rear wheel meaning potentially fewer broken spokes, and possibly a leather (Brooks) saddle as standard equipment.
Disadvantages of the vintage bike include heavier weight, hard-to-find replacement parts, less sophisticated and durable parts quality (unless you get SunTour), and less effective, center-pull brakes.
Advantatges of modern bikes include generally lighter weight, more durable parts, less expensive parts, easy-to-find parts, excellent brakes, and readily-available replacement wheels, tires and tubes.
Disadvantages of modern bikes include unknown reliability for some carbon parts, more upright and twitchier-handling geometry, more fragile wheels, and less flexibility for fit because of threadless stems.
Please comment on these perceptions. I am probably wrong on some things. Finally, since I buy yard-sale bikes, prices are NOT significantly different between vintage & modern bikes. Thanks for your insights!