Just wanted to try something new. Also, my mrp bashguard ended up getting too beatup and bent. At a race in Snowshoe in 2003, the boomerang and bashguard took a large hit and I ended up retiring the guide after that race because the metal was all mangled up.
Everyone will say E13. If you're posting this in the freeride forum then I guess you're freeriding and you should probably get an E13 if you plan on smashing your guide. Also, the E13 is a very simple guide, just a boomerang with a roller and a bashguard. I've seen many bent MRPs though, and a lot with dropped chains. They don't look totally durable.
If you want to race, or want a lighter guide there are also Gamut chainguides which are similar in design to the E13 (boomerang/bash combo) but considerably lighter. They make 2 guides, one with an aluminum bash and one with a plastic one like the E13. I ran the plastic bashguard at Whistler for 4 days and had no issues.
the MRP uses very thin metal, and bends very easily. They are not ment for hardcore abuse. The don't come with bash guards, but there is the option to buy one. E.13 are ment for abuse, and come with the big lexan bashguard. If you ever case somthing with an MRP, you will probably break somthing. As stated earlier, the MRP is lighter, but for FR, I would probably go with the e.13. I have both, and know from experiance about the smashing of the MRP
and.... E.13 Support is AMAZING! (there are actually some members of this board that are e.13 techs)