I occasionally use Photocentric firm grey UV on FL Grey V.2 settings doing the cartridge refilling thing for non-critical parts that are big. They historically have been slightly over-exposed so I avoid projects where dimensions are critical. I’ve only had one instance where cracking occurred a year or so back. I put that down to elevated temperature exposure as I used it for a mould from which I was producing waxes.
Apart from the technical arguments of not wanting to allow the heater and wiper when using third party resins, there are obvious commercial ramifications. Here in the U.K., the photocentrics resin is 1/3rd the price of FL. We also have a big Photocentrics LC-Pro which of course uses their daylight resins. Not to be confused.
Grey V.3 is great resin, but economically, its a disaster for big non-critical prints.