I gotta admit I shoot for $#|t. I know this, I admit this, and I know it is wrong, but I rely on and practice heavily on my laser. I also have the internal Lasermax on my primary carry piece, a Glock 23, .40 cal. I love that it is internal more for the cool factor then functional. LEO's I have discussed it with and most anyone seem to prefer anything that is grip triggered, you shouldn't have to rely on turning it on manually in a tactical situation.
My only argument against the manual turn on is that perhaps in any number of situations, you do not want it on as stealth would be to your benefit tactically.
The internal Lasermax put me out around $289 with shipping a couple years ago, but it has held up fine and helped improve my accuracy drastically. The unit is pricey, but it works as advertised, turns on while at the range and practicing drawing rapidly and shooting quickly. Despite the heavy price tag, I consider the Lasermax to be a worthwhile additional tool to have around. A young 17 and 18 year old couple from the area will also testify that it works well to rapidly deter would be home invaders, the laser seems more real then a black could be a gun apparently.
-jason