I thought I just answered this same question a week or two ago... Anyway, the IR filters suck. Bad. I use 'em for white light covers on some old lights I have. In the dark, they just glow and that's about it. I think an IR chemlight would work about as good.
I also have the Surefire vert. grip. It came with the incandescent, but ate batteries like a MF. So after ten years of that, I just switched out the lamp with a new LED/IR head, and I like it. It is good for illumination in a room, building, whatever, but it doesn't do the same job as the illuminator on a PEQ-2A. Laser illuminators are in a league of their own.
In the future, if I need another weapon light, I'll probably get their 720V Raid. On the other hand, the grip light is pretty nice. Back in my room clearing days, I didn't think I'd like it at first but realized that the only time I used the grip was also the only time I needed the light and vice versa. So they got married.
There is a class 1 illuminator, I forget the name, but it illuminates nearly out to a mile? Looks like a regular, round flashlight and some NODs dealers sell 'em. Lots of folks talk about 'em. The laser illuminators just work better all around, I think.
FWIW, Newcon Optik makes lasers that are class 3 and available to the public. They make a nice laser range finder I'm interested in and I know the army uses some of their bigger ones (27km+). Now I don't know how the lasers measure up, I don't know anybody with one, but the specs look a lot like a PEQ-2A and they can't exactly be total junk if they are making $30,000 laser range finders.