I'll add my 2cents. I've hunted with 3 different BAR's over the course of 18 years...MKI's w/out BOSS (308Win) and a MKII w/ a BOSS (270Win).
If you want the lightest recoiling configuration possible get the BOSS, mine is a pussycat with it. How good is the BOSS at tuning loads? The factory recommended sweet spot for my brand and bullet weight produced 2" groups, my own setting of "0" w/ microadjustment at "2" I consistently get groups under 1". So you have to play with it, but let the barrel cool. The downside to the BOSS, like others have pointed out, is the muzzle blast. It's pretty loud.
As others have pointed also, triggers are creepy. My MKI had a much better trigger than my MKII, but they all have creep.
And my personal opinion (and that's all it is) the BAR is a Cadillac compared to the Remington 7400...and that's coming from a Remington lover.
I've never shot one of the lightweight receiver models.