I'm looking at either 2012 K2 Formula or Company bindings, but as I want last years, (partly for cost and partly because I prefer the style), I have to buy them online. I have '10-'11 ThirtyTwo lashed boots in size UK10, (US11). What size binding would be best?
Have the 2012 Company in large and it's a pretty perfect fit with a 9.5 boot. Should work with a 10 but it'll be close in my opinion. Best bet is to go try it out yourself to see what you're comfortable with.
Not sure if it is too late but I just got last year's K2 Company bindings for a size 11.5 Salomon F22 boots. Bought L and XL to test both. Went with the XL since it gave me more flexibility with the adjustments. I was maxing out the settings on the L. You should probably be fine with L since you have a 10.5 boot, but might want to check XL just in case.