I haven't heard the RS6, but I would expect that there will be a considerable difference between them and the Emotiva. For starters, you will need a sub with the Emotiva. You didn't mention it, but if you don't have a good sub now, consider it part of the system cost. Then again, you will probably want to use a sub with the MA's as well for LFE.
I have heard the Emotiva speakers. I thought they were the standout product at last years Audioholics event. They sounded very detailed and neutral, pleasing to my ears. They are solidly built and were demonstrated to take quite a bit of power without a hint of strain. Combined with a DSA-1 subwoofer system, I think they will be a considerable performer, both in sound quality and value. But it's hard to judge the Emo's against the MA's without having heard them.