Benefits of the GMU 11 include:
-Price
-Weight
-It uses ships power instead of 5V from the GSU.
-Using the CAN BUS (and freeing up Serial Ports, which is less of an issue now that more and more LRU's are also using the CAN BUS).
-Mounting
Regarding the Can Bus, it is important to remember that the can bus is laid out as a backbone, with two distinct "terminations"/ends. When you have units spread throughout an airframe, the wiring doesn't have to make a bunch of jumps to and from your panel for every unit (as long as it is somewhat methodically designed.)
So, RV-10 Can Bus length might be in the 40-50ft range with wingtip and/or tail cone mounted LRU's.
Another data point regarding a tailcone install:
The GMU 11's in the factory demonstrator, and One Week Wonder RV-12iS's both sit about 32" away from dual fuel pumps and a roll servo. The interference tests conducted passed with flying colors

YMMV
All that being said, those guys at Stein do good work, and could very well be taking things into account that I've overlooked.