I'm looking to get a dual ring chain guide. I've narrowed it down to the two models. I can get the MRP w/ ISCG mounts for $125 and the E-13 is $165 plus $25 for the ISCG plate. Is the E-13 worth the extra $$ over the MRP? All i want it to do is hold the chain on the ring. Nothing else. I also don't want to have to replace the BB. Incase it matters, this is going on a Specialized BigHit Comp.