I have the 2011 XTR shifters with a 2011 XT RD. I picked XTR for the shifters because they have three cool features: 1. direct shift (the RD moves with the push, not the release of the upshift lever) 2, dual upshift action (trigger or thumb-push) 3. the ability to upshift one or two gears at a time. Perhaps the 2012 XT shifters will do all this too (the 2011 don't) but I love my XTR shifters. They are smooth yet crisp and never mis-shift. The ability to be able to upshift (move to heavier gear) with either the trigger action or the SRAM-like thumb-push action with the same upshift lever is awesome - I use them alternatively depending on my hand position and the conditions. Then, the ability to upshift two gears at a time immediately with one push is supercool e.g. if you've just crested a rise and want to keep hammering without waiting for the 4 clicks (in-out + in-out) that it would take with a cheaper lever to move two gears. So, you guessed it, get the levers. Or, if XT will do all the above, you may just get both a RD and shifters for the price of XTR shifters, in which case i'd do that.
