I purchased some Rimz and while they work fine, once I got my BMT tool I liked it so much that the Rimz became pointless. The Rimz aren't exactly cheap either, so I'd say save your money and put it toward the BMT instead.
As far as durability goes... the BMT is machined from a solid block of Delrin. The demooner side has a metal insert that actually puts the pressure on the cases to pop them out and a metal post for the loader part, and the loading side has magnets to retain the empty clip , but the rest is Delrin. Delrin is used in lots of high wear applications because of it's durability. I have no doubt that barring abuse, it'll outlast me. Even if it did eventually wear out, I like it so much that I wouldn't even think about not replacing it. It's a great tool and I highly recommend it! Trust me, use it to load a hundred rounds or so and you'll be a believer.