70-400G or 70-300G?

+1. The A77 AF is a big improvement and the ability to micro-adjust really pulls more out of a lens. On the other hand 24MP are harder on the lens than 16MP (resolving power and AF accuracy).

I'd keep the Tokina and see how it performs. I have the Sony 70-300G and Tamron 200-500. Before that I owned the Sigma 100-300mm f/4 and later the Sony 70-400G. The Sigma and the 70-400G have a slight edge in IQ and are both terrific lenses but for me the lower weight and smaller size of the 70-300G makes it more practical.