Anyone using the E-5 for sports?
Shooting low level MMA events, you're going to be shooting in the ISO 1600-3200 range for small civic arenas with spotlight capability. If it's more low end fighting than that then you're in 3200-6400 range. I think with the f2.0 zooms you're OK on ISO BUT if you're going to be doing a lot of this you're going to want 2 bodies - you'll need a wide angle lens for action that's close to you but you'll want a longer focal length to be able to get tight shots of action on the other side of the cage.
Now, MMA is not a sport that relies a lot on focus tracking - you want quick and accurate focus acquisition but your subject isn't running through focal planes - so the advantage Canon's ai-servo gives you in focus tracking really isn't needed.
So I really don't see a compelling reason to buy Canon just for MMA - the E-5 seems to deliver enough of what you need but I'm not sure there's a good single lens solution and switching lenses isn't practical so the one downside is probably requiring two bodies.
Truth be told, while I enjoy MMA, I found shooting it to be a royal pain as you typically have to shoot through the cage (platforms are usually reserved for video) and that cage is a royal pain to deal with. I personally hate having the cage visible between me and the subject so I shoot with lens right up by it so you don't see the links. That makes for uncomfortable positioning - especially if there are tables between you and the cage. Some people shoot from further back - but there are two issues: 1) focus - you don't want to be so far back the camera focuses on the near cage wall - so you need to be within the min focus distance and 2) I don't like the look of the links in front of the subject. I don't have a lot of MMA experience - so others can perhaps give you some better advice, but I have shot it so I thought some experienced advice is better than none: