I've run Mefos for a while on KLR's and just put a Mefo SE on the back of the 990 (TKC80 up front). I love the Mefos but I will try some different fronts. 606 most likely since I want something more "dirty"
I have been amazed at how aggressive the Mefo hooked up in back while still keeping the bike commutable on street. Just ran the bike form Portland OR to LA and it felt great.
Not a huge fan of the Mefo front. Feels weird on street and not to predictable off road. On recommendation from the guys in Alaska, I ran the Mefo front backwards and that helped tremendously especially in mud.
I will keep Mefos on the back and experiment with the front till I find my sweet spot.....