Thanks. It will be used mainly with a 500mm f4 L IS, though I'll now have the option of using a 2x TC as well as the 1.4x along with the AF/ISO benefits it brings in comparison to the 7D (which itself is a great camera).
This is my thinking exactly. The single drawback is that I'm finding hard to justify the cash spend on a 500 F4. Also the prospect of lugging it around at my age!
ATM I'm just concentrating using it with a 300 F4 and 400 F5.6 with both Kenko TC's.