As far as cash games go, never was offered or know of anyone being staked.
This past August at Foxwoods, played a $3,000.00 buy-in tourney. A friend of mine wanted to put up half the buy-in. The deal was cold 50% of any winnings with the buy-in cost never coming into concern. Of course I didn't do it. With my luck and with a backer would be the one time I won the whole damn thing. (by the way i wish I did it-I'd be up $1,500.00) That was my only personal experience with a stake offer. I think C. Moneymaker even though he won a seat, was backed with a full buy-in, in the wsop
he won, and chopped 50%.
I would guess with a cash game, the backer's money would have to be returned first before chopping any profits. Rake-back should be the same as the profit chop. I also think you should be better then 50/50 on the chop, considering not a mega purse guarantee along with the odds
of hitting a pay seat in a tourney. Cash game allot of work on your part. Profits compared to purse play allot different.