I use a Safariland ALS on GCode RTI hardware (the 'duty drop,' I think) for G19 + TLR VIR2.
Works perfectly. But, things to be aware of:
1) In order to secure the gun, the holster locks up against the barrel hood cutout, and has a small strut to hold the muzzle. It will NOT work with extended/threaded barrels, compensators, or anything else that extends forward of the slide.
2) Because of the hood lockup, it may not work with some aftermarket barrels that have a larger breech area than stock. Everything I've seen commonly (eg LW) has worked, but something to be aware of.
3) Taller than stock front sights may drag on the locking mechanism and shave small bits of plastic.
4) The GCode hardware does NOT have adjustable cant. I don't think you need it, but there it is.
5) The standard ALS 6xxx-something holster will not work with optics. It'll fit almost any light that doesn't have a lower laser fin, but optics are a separate holster. That's the "DO" models, and they can be significantly more expensive.
You should settle on the gun configuration first, and then choose the Safariland that will fit it. GCode is good no matter what, their universal pattern hanger fits on all Safariland holsters, and is absolutely recommended.