If you have the cash, splurge for the top end model. I play lots of Minecraft on my 1.6/4 and it runs pretty nicely at normal render distance+better lighting mod+occlusion mod. Runs alright at "far" distance too but skips here and there.
I felt like I had a less than perfect time running it on the base 1.4's in-store, but I didn't have extensive time with them as I do my own Air.