It's a tough call. I'd love to go Carbon for my 2012 Race Machine. It seems to work for The Bald Chimp anyway... Here's what [he] had to say...
"Well……….I can let you test ride both if you want, although the SIR is set up monster right now, we are both the same size (from the waist up so fit should be close). Here are my thoughts and I’m like you an old steelie fan. I love the SIR, everyone should have one, it’s a great workhorse and the ride is brilliant. Not all steel is equal, a good nimble well designed 853 frame will ride circles around most (heavy) lower rent 4130 frames. I can’t stand the ride of a Karate Monkey for example. That said it took me nearly all year to warm up to the AIR and it really only came together for me at BT and its awesome. So light and sick fast, I think I wasn’t confident on it and now I get it. Now I want it to weigh sub 17 lbs so it is my quest to race rigid in 012 to shuck some weight. So what am I telling you? You need one of each."
I think one of each would be my first choice fo sure, great idea...but my kids need to eat. In reality, it would cost me more than double to go carbon. I'm wondering if it's really worth it. I do crash a lot, but I still have a few steel bikes around for crashing.