SGs are fairly difficult to replicate for other reasons. The neck pickup is in the "wrong" place, the neck joint is thin, and the Gibson scale length is also important to the SG tone.
I think "resonance" has become a bit of a buzzword in the guitar community. Resonance has started to mean "good" when in reality it should mean "dark with dampened sustain". It only makes sense that if a guitar is resonating all this extra energy, it loses sustain. For this same reason a highly resonant guitar (like a hollowbody) would loose treebles.