said by bburley:
MPLS was supposed to make the link a bit faster
I believe that was true when 802.11n first came out... MT had a problem with poor performance on WDS links, but they fixed that quite awhile ago. I looked at the Wiki article, and it appears nobody has updated it since then. When I set up my first few 11n links, I did have to use MPLS, but as soon as regular WDS bridging performance was fixed, I dumped the MPLS stuff since it was much more complicated than the simple WDS setup. And it does pass mac addresses properly.