Thanks for the advice. Normally shoot much shorter lenses and normally 3 primes - 14, 24, 28.
The 300 was meant to be a bit of a fiun lens. I'll certainly play around with it but a 28-200G is so cheap that I'll probably get one of those anyway and see how my long lens usage evloves over a few months. The one which I end up not using, will be the one I sell on.