Are mercury vapor or metal halide FCO’s really all that rare? How common is it to find an FCO fixture that isn’t HPS. In my experience, I’ve only seen non-HPS FCO’s once in Grove City Stringtown, Rd which were MH.

But, around you, are there any HID FCO cobra heads that are NOT HPS???

I don't think I've seen a mercury vapour FCO before but I've seen metal halide and induction FCO cobraheads before.