I think it's funny you consider 2.1 overly slanted towards gunner engi marine borg, when the next 2 most common classes have gotten shafted since 2.1. Recon is nowhere near as useful as it was in 2.1, the blind change being nowhere near as useful as strafe flying, and arsonist lost a second on his freeze time.
As for the 4 main classes changing since then, marine got good hyperblaster, gunner got a better mega, and borg/engi changes more or less balanced each other out.