Have done a bit more investigation. Im not saying I'm commiting to the top dogs, but $$$ wise, I'm putting Rupes and Flex on the same playing field. There's about $350 (debatable) worth of pads, sanding disks, brushes and polish not included with Flex to bridge the gap enough.
It seems Rupes likes/needs Rupes pads and their pads prefer their polishes. Apparently some formulations degrade a Rupes pad? So it's a strike against Rupes for locking you into a system, assumimg I have got that info right. Anyone know anything about that?
Flex include 3 plates up to 75mm, Rupes a 30mm and 50mm with a 30mm sanding. Not here nor there really, doubt I'll ever sand anything or use a 75mm, as jumping from a 30/50mm pad to 150mm pad would be no problem.
Rupes looks more ergonomic, though I haven't established its battery capacity and that could have something to do with it. I think they both recharge faster than use, so probably irrelevant.
I'll do the math sometime on long term pad costs. I think Rupes will lose big time.