kreider, I hear ya and agree 100%. Rolemaster, with it's myriad of options, really doesn't support that style of play very well. I think some have missed your point here.
Some suggestions were presented, but the idea of keeping different chars for different GM's is unwieldy at best. The best, by a longshot - If your gaming group does like RM then spend some time deciding, as a group, deciding the exact ruleset to use and write it down. It will also be far less confusing if everyone doesn't need to remember what rules go with what GMs.
We are just now switching to a new GM (from myself) but he is adopting all the same rules that we have been playing with. He might add some house rules, which we will all adopt as a group and add to our master rules document.