If you plan on doing the set screw, do it first, then ask if you even need to polish. Why? I set up my DPMS/Stag LPK in an AGP lower.The set screw adjusts most of the creep out to the point it justs breaks, maybe a 1/10" travel. None of the gritty portions are even travelled. Why polish what doesn't get used?
That alone changes the trigger 50%, the other part is the lighter spring tension. On a hunting rifle, I don't want a light target trigger. There's too much banging around in the brush, exactly like field manuevers, which is what the Army requires the minimum 6 pound pull to prevent discharges. No, the finger doesn't have to be in the trigger for something to snag it falling down. It happens.
For $0.00 and 3 minutes spent adjusting the screw, it's about all I need. If it was a precision range gun, I wouldn't even bother with ti and would have it set up in the finished gun I bought. After I shot it, then maybe with some knowledge of why I was doing it, I could appreciate what it was supposed to do.
However expert some few may be, the majority really don't know how to do it right, and are looking to claim it was done so their rifle will have more credibility points than the next guys.