This is one of my recently acquired HD weapons. The light offers instant-on, constant-on, and strobe functions. $120 from Cheaper Than Dirt. I expect I will eventually add a treaded barrel and supressor.
Apex Hard Sear, USB, and AEK - easy way to get under 4# pull. Really brings it to life, IMO.
I managed to incorporate a add-in mechanical stop on my 4" M&P .45's trigger, it was pretty good before (3.5/3.6#, but a bit of take-up), but with a little tweaking it's at 3.7/3.8#with minimal take-up and nearly 0 over-travel.