Yes, I have these on my S&W model 638, snub-nosed revolver.
They work well, and they do not interfere with holsters or anything else. You only have to replace the grips.
You do not have to illuminate the laser if you don't want to.
It was easy for me to get the laser sighted in with the small supplied allen wrench. The laser sight aim point relative to the point of impact has not shifted.
The small sights on a snub-nosed revolver are more difficult to pick-up, so I think that the laser gets me on target faster.
I can recommend Lasergrips.
I have some on a Ruger SP101 and I like them a lot. If you buy, be wary of the price you pay--which varies widely from retailer to retailer. I paid about $200 for mine, but I've seen them on sale for as low as $165 or so (for the Ruger and Taurus revolver models).
I have a set on my Gov't for those dim light conditions where the sights get fuzzy. I like them, although the dual-axis parallax is noticable.
You'll want to dry fire with them a lot at first, because you won't believe how much your hands wiggle. After a little practice, your hands will steady down.
Get a 2nd set of batteries when you order the grips, although you'll be surprised at how long the batteries do last. I'm on my 2nd set of batteries. The first set gave me quite a bit of warning when they started to go.
I got two, one on a Ruger KP944DC and one on a Springfield Armory 1911A1 GI. I like them so much I'm trying to scrounge up enough jack to equip my Ruger P-85 with them. Alas, they don't seem to make them for my Taurus 66 .357 mag.