I'd characterize carbon fiber's main performance advantages over steel being weight and aerodynamic shaping. The feel is certainly different, too, and CF 'feels' urgent and responsive.

That said, a rider has to be performing at a pretty high level to recognize those benefits. For fast club rides, I don't see any meaningful distinction between the performance of the steel kids or the CF kids (around here), aside from the fact there are comparatively few on steel, and fewer yet on modern steel.

Ultimately, I think the most important differences between steel and CF are in styling and road feel. I haven't ridden a CF bike in a few years, so maybe it's different now, but it used to have a bright, hard-edged chatter to it, whereas steel transmitted a tempered, warmly colored feel. Very subjective stuff, and I've not ridden enough of either material to speak definitively, though that basic impression comported with others' impressions that I'd heard.

But to the statement that it's harder to make a competitive steel frame, I think that's part of the reason those frames are so prized by some, for their special, unusual nature. When every carbon frame is light, stiff, and exotically shaped, they seem mundane. Believe me, there are plenty of mundane steel frames out there, too, so that's not a jab against CF exclusively, just to point out there are more options in steel frame design to really set one apart from the rest, and less opportunity in carbon.