I measured and compared my 2.0 slide, internals and USB to the Plus. They are identical. I even swapped the slides and they worked fine.Thanks. That's about what I figured.
I had an extra Apex sear in my parts stash so I put it in mine yesterday.
Just the sear alone lowered the trigger from 5 - 15.5 lbs. to 4 - 4.7 lbs.
I'm betting S&W was smart enough to not create a new slide for it to keep the product line simplified. PLS we called it at ITW.