It certainly won't hurt, as long as it fits. Anytime you have only smooth-machined surfaces as the bearing surface, and you add a roller to the mix, it's going to cut down on friction, stiction and resistance. In this case, your smooth-machined surfaces are the cam pin body and the machining of the cam pin groove into the bolt carrier body. Putting a roller in there certainly cuts down on that resistance, et al.
Since this would be something that would have to be measured, the question would be - does it cut down enough in order to enhance performance? Maybe not. However, will it cut down on wear on those parts, over time? By it's very nature of not have metal slide on metal, it will add to the longevity of those two pieces.
Just another way to look at it.
P.S. We're currently seeing this for the first time, in triggers. The Elftmann Trigger...
Definitely more to follow on that, as time goes on. <thumbsup>