I was in your position just two years ago. I'm probably a bit smaller than you are - I ride a 44cm, so I found my choices to be quite limited. Well limited is probably an understatement. I found one high end bike that would actually fit me and fortunately I love it. I have a Ruby and yes, even in a 44cm it still has 700c wheels and does not have a compact crank (which for most crits would be pretty darn useless...).

As far as breakage goes - I know carbon sometimes has a bad reputation, but remember if you break Ti, it can be hard to impossible to find someone who will/can repair it too. In fact the only person on my team who has broken a bike in a racing crash, broke a ti bike....

Like the others said worry first about how the bike feels and fits than the material - unless you know you end up on the ground a lot, I wouldn't worry about breaking a frame. If you do crash often, forget Ti and carbon and go for a light weight steel frame....... (you might have to go custom for that, but Kona's doing one made for racing this year!)