I have no experience using the 300/2.8 II, but from what I've read, it is one of the best of the superteles, especially considering value. I've read it takes the new III teleconverters very well IQ wise. I hope the 7DII has significant improvements over the 7D but I'm thinking it may be way more expensive. We'll have to wait and see. I think my next camera will be my first FF (5Dm3). Neuro usually has tried and compared most cameras and lenses combinations and I really trust his opinions and comments. I know he really likes his 1Dx and 600mmLII.