I don't race, but ride what I consider to be a respectably light steel frame and absolutely love it. Lightweight is vastly overhyped due to the profit margins on expensive bikes/parts. Stiffness is arguably a more important factor for competitive racing, but IMHO is unlikely to materially affect performance riding with local clubs. Good training, nutrition, and overall fitness sure will, though!
I was a bit disappointed to read this in CN's update on Tour bikes
this morning (my emphasis added):
"Officially unveiled two years ago, Giant's TCR Advanced SL includes all of the design features now considered virtually compulsory for modern frames
: a tapered front end, an extra-wide bottom bracket shell with press-fit cups, an integrated seat mast, and optional internal wiring for Shimano's Dura-Ace Di2 system."
I don't mean to pick on author James Huang as he's just telling it like it is as far as "high end" racing bikes are concerned. However, my not-exactly-ancient (2006) frame has a 1" round head tube, normal ITA BB shell, a round seat tube for a 27.2 mm post, fully external cable routing, and a horizontal top tube to boot. It also fits me better than any production CF frame ever will (I'm 198 cm, long legs, long arms, long torso) and rides wonderfully over all kinds of roads. I regularly ride my plastic-bike buddies off my wheel when I'm on the front if I'm not paying close enough attention to them
Additionally, it's durable and repairable, and a known quantity in terms of longevity. If your post had said "I've got a 90's carbon fiber bike..." then I don't think many of us would encourage you to ride it
Fit and comfort, fit and comfort, fit and comfort . . .