After a few Hundred rounds through mine, it smoothed out to a nice 5.5# (approx)... Just about as nice as my G26. I wouldn't really want it lighter than 5#.
I never really thought of the trigger as being a long, or heavy pull to begin with though.
For just a couple hrs of your time, you could try the Burwell's M&P Trigger job.
S&W M&P Trigger Job