I think the one area where GS has the edge was in freeing up availability for premium class miles seats or upgrades. There were various things that GS agents could do to accommodate you moving around inventory. It was somewhat arcane and basically assumed you were spending time on Flyertalk to even understand what was possible. Agent knowledge was also a bit uneven so sometimes it took some effort/HUCA. +1 GS
GS today is a sad shadow of what it was back then in this regard. Though it still may be ahead of CK/360.