I've had a several of the carbon 600's break on me, so that is a concern, but I agree that 600's are probably the best choice for your setup (assuming you are drawing close to a normal 28" draw). When they break, I think it's because I miss the target and the side of the shaft gets smacked against the target shed or some other hard object. If it doesn't break on impact, then it can still weaken the shaft at that point, usually near the fletching, so that it breaks later. Gold tip recommends flexing the shafts before you shoot them, which should catch that kind of thing before you shoot the arrow. I try to remember to do that now that I've had a couple break on me.