I have a really big problem with the fact, that this is for pvers only, arena and rated battlegrounds, those are for serious pvp players, it requires a special set of equipment, and to be honest, if you want to be anywhere near "high rating" you HAVE to be able to adapt to a situation, something that PvE does not have.
On the other hand, we have PvE, this requires another kind of gear than the gear for PvP, so naturally, PvPers cannot join and expect to be of use, and vice versa.
Blizzard, this brawler's guild thing you got going, has a really great potential, but you have to have to have to have to HAVE to include both factions of the game, both the PvP and PvE community - as stated earlier, I think the best method to make it fair for everyone, is to simply set a maximum gear value, as you did with challenge mode heroics.
This will never be competative when the group of players with the most time spent in raids, somehow finds themselves facerolling through the fights, while the rest of us, can't even get past the simplest of fights, because we lack DPS.
This is a long !@# post, the point is this:
an enragetimer is needed for sure, but it should be set so that it can be reached with x amount of gear levels, such as 463