DrummerKev - thats horrible news, Im sorry for your lose. My royal gramma and 6 line get along just fine. There wasnt really even any territorial fighting. Maybe mine do well since my 6 line was in 1st and the gramma is bigger. the gramma wont pick on the 6 line cause he was first, but the 6 line wont pick on the gramma cause he is too big (at least I hope that is how it works).
That said, I wouldnt be gutsy enough to put them in a 10 gallon tank together without a lot of hiding places.
Even more important though, I wouldnt add 2 fish at a time to a 30 gallon. I have a 29 gallon, and I cant imagine it having enough biofilter to support the addition of 2 medium sized, and somewhat active fish, at the same time. You already have the 2 percs, I would just add:
Yellow watchmen
Lawnmower blenny
6line
Gramma
in that order and one at a time. also what is your filtration? that is not an unmanageable bioload, but I hope you have good filtration for it because it is kind of high. Also a small pygmy angel is ok in a 30 gallon, but if you do that I would eliminate 2 of your fish. Since a pygmy angel is bigger and usually a little less hardy. Hope I said something helpful in that mess....