2011's got the heavier crank as well I believe
yes, I believe that the 2011 got the heavier crank. The only visible differences between the 2010 & 2011 (that I know) are the plastic stick-on swing arm protectors and the hole in the brake lever (to let high speed air thru - not that u go that fast & they should be replaced by something better anyway)
Sitting on the 2 bikes (pre & post 2012) you will notice a small but noticeable change in riding position too, with the post-2012 bike having wider bars and a narrower, less comfortable seat - this will be a personable/individual preference. The low/mid rev range drive is better on the 2012+ bike, but many find there is enough power or they have changed exhausts and fuel maps anyway. The TC was updated in 2012 too I believe, to make it smoother, but many still don't like/rate it too highly. Other than that, the visible differences on the 2012+ bikes are heel plate design, small winglets on the side fairings, rev counter graphics and tail design (narrower & got vents in the 2012+).
i was in a similar position to you 2 years ago - I bought a 2011 Thunder Grey, as I changed things anyway (exhaust, ecu, TC, levers, seat, etc) to something better than a standard 2012+ bike anyway & I love the colour.
a long winded way of saying "not too much difference, all of them r brilliant and you can't go wrong if you get it for the right price in the right condition". Best of luck with the purchase & u will love whatever u get