If your shooting for the ten ring, or trying to shoot a smiley face on paper I bet they work pretty good.
I too have fleeting eyesight but I have owned glocks for almost twenty years and basically point shoot to center mass good enough at self defense distances.
I personally would not count on any electronic device that takes the place of my rear sight if I needed that sight to place an effective shot.
I do have a revolver with a laser grip, and the laser adds accuracy no doubt. Six shots one hole all day long. The laser is a tattle-tale when it comes to staying on target while pulling the trigger. You can watch it bounce all over the target while you go through the motions.
I guess I could consider it a training aid, but the only way it would ever be on one of my carry guns is if it also had a notch built into it to use as a sight if it failed.
Thanks for reading. That's my two cents