I use mostly harp stuff, but I have added RM crit tables (including all the results, like must parry and no parry, which works sweetly), using it with HB#11, which works fine at the moment. In addition I?ve added skills: Silent Kill and Nerve Strikes (from MaC), I?m also considering adding long distance running and sprinting, but as of yet I?m unsure if I need it.
I do like the ATs in RM, but I find it easier with DB and my players seems to like that too, but introducing the ATs might not be a bad idea, although the mention of CC here intrigues me, I might have a look at that one too, after next payday.