I'm a fan of the new KAC mod2 gas system. It uses a castle nut and compression fittings in lieu of taper pins or set screws. Developed for this is the new urx 4 IBN rail, which is unlike what you are speaking of, in that it does not slip fit and clamp at a collar. The IBN rail torques into place as the barrel nut. The two combined, configured for their keymod mounting system, have the best dimensions and feel of any rail I've run. In addition, the mounts are without bulk, leaving the internal space free and clear. This and the hole pattern, makes for the best looking of any rail I've used.
KAC makes an IBN rail configured for the mlok mounting system. But the nature of this clamping system adds bulk, and takes up internal space. This and the hole pattern, is not so attractive to me. I tried to learn to like it, for future versatility, if down the road I needed to mount something that would not work with keymod, but I am set in my ways, and have come to terms that I'll not change my preferred setup.
So, my posts on this subject are not to say, one is universally superior to the other, but to say, depending on intended needs and wants, either can be superior to the other. For some, neither are good, as they find superiority in a completely different rail system.
