I had a small problem with laser one. Returned & replaced by S&W. Fortunately I had found the correct laser adjustments earlier (the manual described a procedure for a sight that had been prepped at the factory. The procedure would not work until the prep had been done. The sight does require some delicate maneuvering to reinstall. Fortunately, it's an easy gun to clean and a damp cloth works on the polymer. The sight should not need frequent removal and reinstallation.
S&W published the correction then began setting sights before shipping the BG38 and only slight adjustment was needed. Then they reverted to this procedure on their site about the sight:
Both the gun and the sight have been working fine ever since. The sight is slightly inconvenient to switch on but the offside thumb, left on me, can activate the laser then slide down into the Jerry Miculek thumb-over-the-backstrap hold.
I use the laser to help train whatever hand eye coordination potential I have left. I alternate strings of 5, a cylinder full at a time, laser on, laser off at 7 yards at an 8-inch circle, a paper plate, or some such, as fast as I can sense I'm back on target.
Lots of dry firing and a lot of rounds down range have smoothed out the trigger and the laser during dry firing is instant information on the hand and eye thing. The cylinder release is truly ambidextrous. I think it's a good feature.
I have a 642 without a laser for EDC and I switch off between the two.