Flow restrictors, efficiency, soft tip bolt, the feedneck clamp on the geo 3 is adopted from the csl and is way smooth and wont wear your anno, they made a few little mods to the can on the bolt. I am very impressed with the changes in the geo 3. Go with it.
AIR EFFICIENCY! Really not a huge deal until your field only has 3000 air. I have a 2 and 3, and I think the 3 is a slightly smoother shoot and is definitely better on air. The 3 is still being broken in so I expect the shoot will get even better. Really can't go wrong with either. Budget= go 2.0 not 2.1 because it is the same marker as the 2 with no performance upgrades ( looks cool with POPS and angled macro line). If the budget is more flexible go with a 3.