I went with the Armalaser. I had an Amazon gift certificate, and some rewards points that brought the out of pocket expense down to about $45, which is well below my impulse purchase point for gun related stuff.
Trivial to install. It intrudes slightly into the trigger guard area, but even with my big fingers this was not a problem.
The "switch" is a wide silver strip inside the trigger guard. The slightest touch activates the laser. (It turns itself off after a little bit.) It's on or off -- there is no pulse mode. The manual suggests touching it with the thumb of the off hand if you'd rather not have your trigger finger inside the trigger guard.
In indoor lighting, it's one bright little sucker. Outdoors, in full daylight, it's visible, but I'm better off with the conventional sights. I figure, outdoors in daylight is not what it's for. At night, I can paint a big bright dot farther away than I'd have any business shooting.
I took it out today, to try it in real shooting. This is not a particularly easy gun to shoot, and I can't say the laser helped me make any magical precision shots. This will take practice, and I will need to seek out a low light situation to try shooting in. Towards the end of the session my hands were shaking, which is unusual for me, and the red dot was dancing. This will take practice.