A few weeks ago I was on a 319 flt in F where someone "supposedly" paid for F and was downgraded. Apparently at the beginning of boarding the FA mentioned to the F paxs that F was oversold and they'd likely be offered $400 comp to sit in coach (I hadn't boarded yet). 10 minutes later a supervisor came to 2 paxs and offered them $200 comp, one guy went peacefully the other put up a fight. The supervisor insisted the computer picked him for the downgrade and the compensation and that any further compensation would have to be requested via complaint (email or phone). The guy finally went back but I thought to myself $200 seemed rather low. Low and behold 2 GS members were the ones that replaced the downgrades.