Wylde chambers are not unique to Rock River, although few other makers are in fact using them yet, and none of the other large makers that I know of. I do believe they will catch on, as the few makers using them, including Rock River, seem to all be known for building incredibly accurate rifles. One other gun maker I know for sure that uses a Wylde chamber in their custom uppers is White Oak Armament; I have one of their service rifle uppers with a Wylde Chamber
. White Oak rifles too, are known as being leading competitive match rifles. There are probably a few makers using them too, but I haven't had a chance to look them up.
Anyway, the bottom line purpose of a Wylde chamber is to allow you to have the best of both worlds: the ability to shoot military 5.56 ammo, plus the ability to safely shoot .223 ammo with reliable extraction and match-like accuracy. A Wylde chamber is thus an improvement on the SAAMI chamber that has traditionally been used in match rifles. It's good to have a Wylde if you want to shoot both types of ammo, while still having match level accuracy potential. Some people view it as a bit of a compromise to enable you to shoot both, but on the other hand, Rock Rivers are some of the most tack-driving AR's out there, and are winning a lot of matches, so I have a hard time viewing the Wylde chamber as a compromise.
Here's how they define a Wylde chamber: