Anyone out there use one of these? What are your impressions? How do they turn on and off?

IPSC_GUY sends

I have one (LaserMax Guide rod replacement) in a Gluck23. Works by a replacement take down bar being pushed either left or right.

Always works, battery life is great, extra set of batteries is stored in the Jentra butt plug. Mine is not accurate, at 25 feet shot is low a foot and right 6 inches. They are non-adjustable.

*IF you have a reason to have a firearm in a self defense mode, they can be used as a warning per se. Bad guys often learn from Hollyweird, and think the laser on them means they are dead. That said, I have read from Ayoob & others that this is a bad thing. Its an escalation of threat or something like that.  YMMV.

Accuracy-     1
Workability-  8
Reliabilty - 10
Coolness-    10+

I have two of these units, one in a G17 and one in a G19.  I've had both for several years without the first problem.  Mine must have been made in the middle of the week (as opposed to CavVet's Monday-or-Friday model [:D]) because mine are spot-on the smaller plate of my 2-plate spinner target at 10 yards (30 feet) - makes that thing sing and dance all day long...

edited to add:
Like CavVet said, when installing it in a Glock you replace the takedown bar with the new, included extended switch/takedown bar - left or right is on, center is off.  This isn't a problem in most holsters, but can be problemmatic in a coat pocket, etc.

You don't mention the application in your original post, so please note that the on/off swith is different depending upon the firearm.  For example:  IIRC, in the Beretta, you replace the entire takedown-lever assembly - the new replacement has a push-button for on/off.

edited yet again for one last addition:
IN MY PERSONAL OPINION, if you want a laser for a Glock or similar polymer-framed pistol, the LaserMax is a good choice (internal, fits std. holster).  But for a Beretta, 1911, etc. I would recommend the Crimson Trace Lasergrips instead (easier installation, less expensive, also fits std. holster, & ADJUSTABLE [although mine needed no adjustment out of the box]).  I have CTLGs on two of my Berettas and one of my 1911s - I haven't had them as long as my LaserMaxes, but still no problems yet...

Hello
This would be going into an STI 2011 so the crimson trace are not an option and the 1911 version is somehow adjustable so that is cool. considering an M6 but i like the fact that these are inside the gun and don't require an new holster.

IPSC_GUY sends

I have one in a Glock 23. Easy to install and switch on and off, but the alignment and accuracy leaves something to be desired.  Sent mine back to the factory with a grouping showing the errors. Came back with little improvement.  At 50 feet its off by a 3-4 inches - not a big deal for some - depends on what you are looking for w/ a pistol.

Of the laser systems I've used, the CTC grips are the only platform I'd consider carrying. Pushing buttons with your trigger finger isn't my idea of simplistic operation.
There are Coupons flying around online for the Glock system that bring the cost down to about 500 bucks. The only negitve thing about this system is you'll need a custom holster to accept the housing.
Yeah, it's a lot of cash, but not a whole lot more than a Lasermax. Of all of CTC's grips, the Glock system is the best they offer. You only have the vertical axis that will ever need any adjustment, so your paralax problems will be minimalized.
Frame mounted lasers are too tactical for my use. Pressing buttons while someones rushing you isn't very appealing.
If you're just farting around at the range and using the laser to see how your trigger pull affects your aim, any laser sight system will work. Hell, a laser pen taped to the barrel will show you that for much less money.
Blinking lasers is rather worthless IMO. The range you're shooting a handgun isn't affected by your limited eyesight. The blinking laser is questionable at best if it even helps, at least in my personal experience. Plus, the blinking hampers testing your trigger pull vs. the dot wiggle.
Another huge point for CTC is their customer service. They've got one of the best customer service departments in the industry. I cracked a dust cover  on the port side pannel for my Elite II and I talked to Mike Z. on their forum and he said to call up and he'd take care of me.
No wait on their phone system and I was talking to a live body. Sent me the replacements free of charge.
They fix problems no questioned asked.
If more companies were like them, even the Communists would say that Capitalism is okay in their book.
-Steve

... WTF? I'd take it off man!