I'm a pretty high volume shooter. I will say that it took me a while to get used to the high mounts, but after a few thousand rounds it remade my reflex on cheek positioning. It doesn't affect my normal shooting any other than prone stuff.
HOB is affected, so you need to make changes really close in, but again its just a volume thing.
On lasers vs passive: Lasers are fantastically fast, but passive is easier to accurately place rounds. And the obvious: If you train for any sort of real world reasons against anyone that may have NVG's its not that great of an idea to flash a ton of IR everywhere. Light discipline isn't just for WL.
The unity stuff is worth the coin. Especially the mag mount.
On my throw around shorty, I use the 2.26 SKD PRO mount with the unity mag mount. Works great and didn't have to drop extra cash for a mini but she is a chunky girl.