By the numbers, brakes outperform cans for felt recoil. No question about that. Not as many cans in the top 50 of the PRS, for what that's worth. However, like mijp5 pointed out, the recoil impulses of the two are very different. The brake is a quick "jolt", accompanied by an enormous concussion. The can produces a slower "shove" for recoil, accompanied by vastly less sound pressure than a brake. With a 6mm, I can tell a difference between the two from the perspective of calling impacts and misses, but they are so close I go with the can and still have no trouble seeing signs of impact on steel from alternate positions. Using my can reduces mental fatigue over the day, and in some cases, I think the lower noise of the can helps me to call shots by reducing the involuntary eye blink that may happen with a brake. Like the other guy said, shooting in a pipe or other confined space with a brake is completely miserable even with double hearing protection. If I shot a heavier caliber (6.5/.308) in competition, I might reevaluate that decision, but at the end of the day I'm out to have fun, and cans are a fun multiplier. And they're cool. And I paid through the nose and waited the better part of a year to get it. So yeah, I use it.
In sum, brakes are "better" but they suck. Cans provide the service of recoil reduction (1) and sound reduction (2), both of which aid in my shooting. You may also find (as I have) that the recoil with a can attached is preferable to a brake. They are more fun (3) and you get cool points they are OAF (4).
Win/Win/Win/Win.
Get you one.
Edited to add OAF, for accuracy.