Laserquest
I doubt it'll catch on as a training thing, since some of the skills that you'll learn from practice are taken away. Things like reloading, getting accurate with the arc of the paint, getting used to being hit by paintballs, being efficient with a rip drive when you forget to replace batteries, so on and so forth.
Point being: It's not paintball, so it's not really practice. Fun, sure, but not the real thing.
And I'm sure that with the price of kitting yourselves out with all that gear, you could just buy a couple of boxes of reballs and do the same anyway.