If you are on the PC, then combustion is the ducks guts, I'd use it over AE anyday for the colour correction and paint tools. I find it more intuitive, but then I was brought up on Infernos and flint/flame systems, so it was already familiar to me I guess.
But like everything it's not perfect, and I have some tools in AE that I still use because I can get the job done faster there. But if I was forced to only use one for the rest of time it would be combustion.
Now that it is sooo cheap it is a much better buy. Oh and BTW, the V4 is looking very nice indeed.

EIther would do the job, but for frame by frame restoration I would only use combustion.