As soon as I got talos (min mako) I haven't looked back, as Dps hes great Some eilte fights I use khem but I try to put the best gear on those 2, Khem has about 11.5k (last time I checked).
As for the other 2, I tried them once to see what their like and that was it. Don't think their has been one fight I haven't done that I've needed help with, some +2 heroic's can be a little tough but then thats what Force cloak is for