Actually great to read this - I've just got myself a 6" newtonian astrophoto rig, and one of my first targets was the tarantula (camera is an unmodded 60D). It came out just as blue-green as yours, and I worried about the reason . Even accepting the lower H-alpha sensitivity of the camera, it seemed a bit much, though I'd read about NGC 346 being more green than red , other nebulae have come out nicely red/pink in the 60D. A 1959 paper on the NGC 2070 spectrum notes a lot of OIII, but the spectrum in the paper didn't appear to cover H-alpha, so I couldn't make the comparison. But... it's reasonable that this nebula has a sizeable contribution of OIII.
I ought to add- lovely image too
