"HID's are a no-go though. I've never seen anything that says/shows otherwise."

They need to meet the same size and placement of the filament specifications, just like LED's, and halogen bulbs to work. Due to the extra cost involved in conversion to HID's (the need for ballast and wire harness) they are not often found in standard sizes and if they are listed as a H11 size bulb they will not fit due to the length of the bulb contacting the fixed reflector shield

no current H11 HID's made will fit. The high beam has no shield and could fit a 9005 HID bulb. Between the cost of a 9005 HID bulb and the driver electronics to make it work you are looking at $200 plus per bulb.
Just like LED needed development to be correctly sized and positioned, HID's could be developed in a similar way but the premium cost makes fitting into a OEM housing problematical on a cost benefit scale. KM