Only at Four Seasons Tented Camp did I genuinely feel that Jason made a real difference to how much I enjoyed the trip. If you generally stay at sub-top suite level (I am happiest in a big open plan junior suite) then you are substantially off the GM's radar. Despite having stayed at many FS over the last five years, and probably spending £15-20k with FS in that time, I have only knowingly spoken to a FS GM once and that was Chiang Rai.
Does it matter who the GM is? It really shouldn't, at a group like FS with corporate standards and substantial cross-pollination of staff. I'd say it matters more at top independent places where a GM from outside can, if given the freedom, really drive a property forward.