what really sets Ronnie's back apart from dorian's is the depth and thickness that it has.
dorian's back has always been very flat and thin looking in the rear double bi pose, but it was detailed, much like Flex's back. Relative to Ronnie's, dorian's back really lacked depth and thickness. It had detail, but Ronnie's back had detail, depth, thickness AND amazing arms. just compare:
and in the rear lat spread, his taper was not nearly as good as Ronnie's. Plus, where Ronnie shows his christmas tree in the rear lat spread, dorian shows his rolls of loose skin.
dorian's back was good.
Ronnie's was in a class all by itself.