I would love to find a Safariland duty holster that would fit the FNX-45 with RMR and a Surefire X300. I'd even be fine cutting one down to fit the RMR, as long as it still has Level II retention (ALS).
In fact, I called them earlier this week to ask. They said "nothing official" is in the works. I'm waiting until after SHOT Show to determine if I'll try to get it to fit in another holster. I've heard (on the internet!) that the FNX-45 will fit in either a Safariland holster for the USP and/or the XD-45.
Right now, I have a Bladetech. I don't like the hood release, as you are basically bending the release out of the way to allow the hood to spring forward. I've also run into a problem, as I switched my Surefire from the QD levers to the "more permanent" locking option, which seems to angle the light slightly upwards-it's getting caught in the holster somewhere. So now I just have to find my Surefire levers again.
I personally find Safariland to the the cream of the crop. Once you've had one, it's hard to go back to any others. YMMV.