I evaluated the C4 scopes at the last SHOT Show. The glass is the same as the comparable MTAC model. The optical performance of all the MTACs is very good for that price point. Resolution and contrast are both high. Burris went with a novel wave washer spring design for the MTAC/C4 AO mechanisms that apparently prevents glare and reduces weight, compared to the traditional coil spring design. The C4 reticle is similar to the Swaro 4W reticle.
HighPowerOptics has theC4 scopes on back order too. We are offering a RingTrue Alignment Reticle Tool free with the purchase of any C4 scope. PM me if you are interested. Free shipping, of course.