I've used just about every kind of chain guide and tensioner out there. I got an MRP last year and initially liked the design a lot. But the thing is made of plastic and requires a torx wrench to install on your bike. While some of us have a full tool chest, there's a few items most don't have (a torx wrench is one of them).
I broke the MRP after about 6 weeks of use. My chain jammed up between it and my ring and snapped it in two.
If you're concerned about durability I'd suggest the Paul, or to get an N Stop and an outer chaintring guide.