Originally Posted by ciclista tifoso

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Good points raised here.

There are a number of factors that play into a 'ride', of course: tire/wheel width, PSI (or lack thereof), carbon handlebars and seatposts, etc. -- all of these components will affect how 'comfortable' a bike may be as the miles add up, regardless of frame material. How much of a difference would one feel on a quality, modern aluminum frame with lower PSI, wider-width tires and carbon handlebars with padded bar tape vs carbon frame? Rhetorical question.

As some have mentioned, age of rider will probably be a factor as well, but I wonder if the difference would really be distinctly noteworthy if riding an AL frame with the above arrangement.

A hi-quality carbon frame would be ideal, of course, but it may not be as noticeable vs. a hi-grade AL frame if the components compensate..

I could be wrong, of course.