The Magpul stock has a rubber back to it that makes it comfortable when shoulder firing. Its a heavier more sturdy plastic and the lever to move the stock up and down is harder to accidentally hit when shooting or handling the gun. In my opinion its one of the best comfort bang for your buck mods you can do.
As far as the bipod/forgrip goes, after putting my first 100 rounds through it its gotten 10 out of 10 from me. It held up very well and felt good holding.