Dave, I avoid Prores on the PC for 2 reasons.
1.You can only playback Prores you cant encode (legally) to it on a PC.
2. It uses qt32server to bridge the gap between fast 64bit (CS6 apps) and older 32 bit applications like QuickTime. This acts as a major bottleneck in the workflow and effectively slows down processes dramatically.
I use MXF OP1a AVC-100 to master to. When I export it goes about 2X faster then if I used a QT based codec like Prores or DNxHD.
Tom Daigon
PrP / After Effects Editor
http://www.hdshotsandcuts.com
https://www.youtube.com/watch?v=DxPrG3WUyz8
(Best viewed at 1080P and full screen)
HP Z820 Dual 2687
64GB ram
Dulce DQg2 16TB raid