When the Heavy achievements come out, I think I'll spend my time playing Spy as it should be fun backstabbing a bunch of these heavy brutes. The next
Team Fortress 2 update will give Heavies some new toys besides Sasha to play with according to the
TF2 Blog. Currently, it looks like the Pyro heavy servers are dying down in my experience as I see a max of three Pyros floating around now when I play on average.