Carlos from Philly wrote a review of Five Ten Team 5.10 Climbing Shoe on March 4, 2010
Three things to focus on:
1) This shoe is a weapon, hands down. It's very specialized; expect to be off your game if you're using it for very vertical routes, slab, dime edges, smearing, etc. Not crippled, but definitely not on your game.
However: the second you move to steep overhangs or caves, roofs, bouldering, precise toe points, heel hooks, toe hooks, foot drags, etc, you'll realize what you're wearing is a very very specific, technical shoe. PERFECT for overhung bouldering more than anything, i think.
2) size this shoe to break in. i bought the shoe in a SNUG size, and i don't regret it. It was difficult to get on, and hurt to wear for more than five or ten minutes at a time. But by week two, everything was PERFECT. Still very snug, but not uncomfortably so. The shape of the shoe has completely conformed to my foot perfectly; heel hooks are ROCK solid (moreso than i ever remember them being), and every part of my foot is touching part of the shoe. no dead space, no shifting, no nothing. Perfect fit...
3) as for sizing, the best frame of reference i have for you is the Evolv Pontas. I wear the Evolv Pontas in what is a PERFECT size 8 after a week or two of breaking in; i wear the Team 5.10 in what is a PERFECT size 9.5 after two weeks. I don't know why there's such an absurd difference in the sizing, but this is it. I can't speak for other brands, but if you wear Evolv and have your perfect aggressive sizing down (emphasis on aggressive; don't size this shoe like a multi pitch shoe or it'll be worthless), i'd bet a size and a half up is what you want in the Team 5.10. That said, i ended up with three sizes in hand before realizing which one was perfect... if you can't find a dealer locally, Backcountry has a phenomenal return policy.