Not yet Chris. Just trying to find the time to run through the various combinations! Yes, I'm sometimes on PH. Usually in the birds subsection of the photography forum!
I'd be very interested in the results. Come October, I shall either be buying a 1DX with 300 2.8 ii, or 5D3 with 500 F4 ii (plus converters for each) to cover wildlife and motorsport.
The 1DX and 300 option is currently winning!