DAJAllred wrote an answer about Five Ten Team 5.10 Climbing Shoe on March 16, 2012
Real late in answering, but here it goes
The Testarosa and the Solution are both stiffer shoes than the Team or the Jet, and both have to be sized way down to be effective. I am a 44 street (10.5) and wear a 41.5 in the Testarosa, but they are TIGHT. I tried on a friends 42 Solutions and they fit well, so I'm betting I'd wear about the same in those. So, thats about 2 EURO sizes down, depending on how tight you like your shoes.
For the Jet 7, I wear a 10.5, which is my street shoe size. That said, I got them more for all day training then true "red-point" shoes, so if you want them supper aggressive go down 1/2 to a full size from your street size. The Teams run about 1/2 smaller than the Jets, so my street shoe size is perfect, aggressive, and amazing.
The heel in the Team is much more low volume than both the Solution and Jet 7 (I had dead space in both, but never had it slipping) and about the same as the Testarosa, though I feel a lot more secure with my heel in the Teams than the Testarosa.
I am a 10.5 (44 Euro) street shoe with a slightly wide toe box, though not wide enough to need wide width shoes.