Son of Liberty:
I've been using a Crimson Trace LG-437 laser on my Kahr PM-9 concealed carry pistol for about 7-8 months now.
And I've been very happy with it.
Here's what I like about it:
1) This model molds very nicely into the contours of the trigger guard and the underbarrel in front of the trigger guard. The fit is quite nice; it's not a bulky nuisance.
2) The laser is naturally activated by the middle finger just by squeezing the pistol grip, as in normal shooting. The laser stays on so long as you hold it on. (Other maker models require the shooting finger to enter the trigger guard and even then only stay on for 10-12 seconds. To save battery, I guess.)
3) The advantages of using a laser are pretty much everything that is presented in the Crimson Trace CD-ROM/video. And they are significant.
4) My batteries lasted for quite a long time, say 4-5 hours total on-time, even after laser targeting and dry firing everyone on TV for many, many nights. [Takes a while for the wife to get used to it.]
Here's the coupla minor points that I don't like:
1) The LG-437 model doesn't have a shut-off switch so that the pistol can be used in non-laser mode. You must use the laser all the time. [Or develop very bad gun handling habits.]
2) The plastic on just about all Crimson Trace lasers is a bit malleable, so that any strong force can move the sights off adjustment a bit. Can be annoying in target shooting. Not enough of a big deal to affect a real life engagement, I don't think. And you can move them back by hand. The "feel" for this readjustment comes quickly.
3) Finding a Kydex or hard leather molded holster for the pistol+laser combination is sometimes a bit tough. [Unless you have a Glock. Everybody makes everything for Glocks.]
I bought my unit new-in-box off eBay for $140. They go around $190 or so from Crimson Trace.
SUMMARY: I'm pretty much committed to pistol laser sights in general and Crimson Trace lasers in particular at this point.
Interestingly enough, I happen to be about the only shooter in the IDPA/IPSC Tuesday night group at the Bullet Hole who uses laser sights. One good reason is that they're probably not "legal" for IDPA/IPSC shooting, but the group has been quite tolerant. Especially since I'm not that much of a pistol shot anyhow.
SemperFiGuy