Sorry, haven't really been on in a while. I use everything from a 13 to a 15. Currently I have a 15 on there. The last scramble I did was the first one w/ the build, and I used a 14, just due to it being tight and technical. I used the 13 a few weeks ago when I was climbing some mountains up Northern NY and VT. But I have been happy w/ the 15T, it doesn't really lug or anything. Imagine a stock, or maybe big 3, w/ a 13.5 if you could imagine that, thats what the 15 feels to me now. Not quite as crisp as a 13, but not luggish like a 14, a mix in between (comparing for a stockish set up as most people have tried those). I hope that makes sense, but of course I have a lot more than the big 3.