@art1437 FWIW as far as
Mammoth goes this is what
last year looked like:
Footloose had and usually does have the most variety of boots although they have reduced their race boot inventory and replaced them with more back country touring boots. You can demo boots and get credit for purchase. +1 on Kevin
Kittridge has less inventory and is geared more towards the average skier. Same demo apply to purchase. They bought out inventory from a xc shop that closed and now have a good selection of xc boots and skis.
P3 has always been the Full Tilt Free ride shop. They are now under new ownership. Same staff AFAIK.
Mammoth Mountaineering is your go to back country shop for demoing and good inventory of touring (and xc) boots.
You asked for the "Best Bootfitter in CA" but limit yourself to Mammoth, depending on your needs, that boot fitter may or may not be in Mammoth.
I highly recommend calling the shops to see when their inventory will be in and getting an appointment sooner than later.......