Just got back from a weekend in Rumbling Bald in NC and after 3 days of bouldering morning and night, I can vouch for the performance and endurance of these shoes. I switched to these shoes from 2 pairs of Evolv Optimus Primes and while the Primes were much more comfortable for my wide feet, as they were A) Only a half size down from my street shoe, and B) Designed to be a little bit wider, but a little less aggressive.
The 5.10's are a full size down from my street shoe of 9.5 wide. I have a caveman foot and it makes shoe shopping, and even moreso, rock climbing shoe shopping very difficult. The Quantums stretch out a ton on the sides and even on the heel area to allow my fat foot foot to squeeze in, albeit, with a good bit of initial struggling. They do require a bit of a break in period to get the maximum potential from the rubber, again, another difference from the Evolv's Trax rubber, which was good out of the box, but had an extremely short lifespan in the toe area. I primarily boulder indoors so the walls aren't nearly as aggressive as real rock; the rapid decay of rubber was very disappointing to me. The Quantums Stealth rubber however has help up fantastically through many indoor boulder sessions, to break in the rubber and to help send some long term projects, and also through my weekend of spirited climbing outdoors and very sharp granite.
The Quantums were GREAT at finding and sticking to tiny foot jibs that my old shoes were guarunteed to pop off of. Some examples of small crystal foot problems, done this weekend are, Don't Run- V8, Rotator Cuff- V5, Chris Klein's Corner- V5. and Torque Master- V6. They are very downturned and very aggressive and take a bit of adjusting to get used to. But once you figure out how to press in with the toes the shoes won't let you down.
They were also very good at holding some pretty intense heels. They held well on Brackish Water- V8, a V8 sit start technical problem with I forgot the name of in the cluster area, and the double heel hook beta used to send Patio Roof-V8.
I can't say enough good things about these shoes. Yes they hurt like crap for someone with wide feet. Yes the heel does cut into the ankle a little as they have the low heel design of the older Anasazis. Yes they do have a tough break in period. But you know they're worth that every time when I finally get them on and know that I can trust them to get the job done on my projects. You sold me 5.10, great job Quantum; I'm looking forward to a future with more sends.