Ian from France wrote:
Sorry i don't agree, i think the 50 would be the better choice, I used a 50D for two years in low light conditions and when I switched to the 5d mk2 I had a real terrible time with the auto-focus in low light conditions, the 50D was so much better; Of course when you can get the focus locked on the quality of the 5Dmk2 is much better, however I've missed hundreds of photos due to this.