Just got the new R310 (before any stores even have them) and right out of the box I'm super impressed. I've been riding Sidi Ergo 2's which are great for rides up to 4 hours, but on really long rides or races the slim fit takes over and I either have numbness or excruciating pain. I got these for the heat-moldable fit--took them out of the box for an 80 miler with 6000 vert. yesterday without even molding them and they were perfect. Light, great venting, good retention straps, and a distinctive look. Can't wait to get them molded and have a really custom fit.
Update: I got these molded (the process is more fun than a colonoscopy--they first mold the insole, then the whole show, then stick a huge baggie over your foot and vacuum-bag it so tight your toes tingle) and now these fit so incredibly well it's like you were born in them. It's been cool and wet in Utah lately so haven't been able to tell how well they vent (it's supposed to be one of the selling points) but otherwise it's a slam dunk. The soles do appear a little vulnerable--the carbon on the heel is exposed and the heel lift isn't as pronounced as on Sidi's, so trewad lightly if you're walking on them and use cleat covers if possible.