We raised 25 CX last fall - got them Aug. 27th. Because October was really cold and wet, the birds used feed to keep warm instead of grow out! We ended up growing them to 11wks, and they were *only* 6lbs! Yes, they were CX. Healthy, delicious, fine, but thankfully, I wasn't keeping track of costs - as it would have blown all calculations!
After processing in the 'heat' of the summer vs. the 'cold' of the wet early winter - I prefer the 'heat'. The cold and damp really got to me. As did the 'warm' carcass and associated smell. We had to keep the doors shut due to cold - and it just was more unpleasant than being super hot. At least summertime processing, the cold water of the rinse hose felt really really good! There was little way to keep warm processing in November on an unheated concrete floor. Yes, we brought in a heater, but the drafts simply made it hard to get the heat to where it was useful (like on my feet!). We brought out scrap carpets to stand upon - damp and cold went right through them up into my garden willies and through my two layers of wool socks (Boy Scouts).
I also found it harder to keep things sanitary in the cold - as I found the doorknobs were getting slimed going in and out (where in summer processing, the door was left open). That's just one example. There were others that I've forgotten. So it's very very possible - we enjoyed the meat all winter long - but just hope for a warm fall!