ARC is pretty good, THM is slightly better I think because of their positioning in fights, the ARC does some real weird stuff with moving back, but yeah, that sounds like a good direction to head. Definitely move away from MDPS as soon as you can.
And yes, when I am healing, I noticed GLA is better than MRD as well - but even with GLA, the ACN's pet can still peel agro, requiring target of the peeled mob and a command to focus.