I always said they should scrap the M16 mag well on the SAW. It would take more than a pound of weight off of the weapon, probably. Furthermore, in my (somewhat limited) experience, the SAW is so unreliable when feeding from magazines that the feature is more or less useless. M16 magazines simply were not designed to work with and open bolt, belt-fed weapon with a thousand-rounds-a-minute cyclic. And from what I've heard, putting heavy springs in M16 mags, to make them work with the SAW, makes them less reliable in the M16.
So, I think they should make an M249A1 without the mag well. While they're at it, they should replace the shotgun-style safety with a regular lever, give the buttstock a proper comb (the SAW often used as an automatic rifle and is fired from the shoulder, without the shooter placing his weak hand on the stock, as he would with a GPMG), and fix the sling so you don't have to tape the clips to keep them from popping off.
Oh, yeah, and get rid of those infernal 200 round plastic boxes.
Just my opinion, of course.