This will be my fifth summer at Momentum and can tell you that every moment of it is amazing.
In terms of the park: Both camps have airbags, access to water-ramps and i assume COC has acceptable coaches, but I know Momentum does. The two biggest differences I have noticed between the camps is that a majority of Momentum's jumps are step-ups or step-overs allowing you to safely progress and learn tricks on any size jump while it appears that most of COC's jumps are step-downs impairing your ability to safely learn new tricks. As well, C uses Whistler's public t-bar which is almost always packed and can result in extremely long waits. Momentum's t-bar is shared by a race camp, a mogul camp and a very small freeride camp of maybe 15 people meaning shorter liftlines and much more progression. As well, the mogul camp and race camp usually leave the hill by 12 make the t-bar almost empty.
In terms of off the hill: COC's compound is located on the mountain towards the base of Blalckcomb, preventing you from easily accessing the amenities of Whistler Village. While it seems to have nice activities it cannot rival Momentum's plethora of activities all around Whistler including, rock climbing, mountain biking, frisbee golf, basketball games, soccer games, wake boarding, paint balling, zip lining, Monkido, and many other adventures and experiences. COC houses its campers in Blackcomb mountain staff housing which is sparse and foreboding. Conversely, Momentum houses its campers in a hotel in the heart of Whistler equipped with an Olympic trampoline in the back, pool, sauna, hot tub, tv's kitchens and everything else you would expect a hotel to have. Further, this hotel is directly across the street from the Village Grocery Store for all your late night snacking needs. Though the two camps have comparable prices, all of your meals at Momentum are free at exceptional restaurants around the village while you have to pay for your own food at COC.
Momentum is fantastic, you will have the time of your life.