Each has their ups and downs.
CPA is good for sites in which the market players are cheap.. IE I assume a website about bonus hunting (don’t do it) or free slots would prefer CPA. Generally speaking people looking for bonuses or free stuff should not be high stakes players.
Negative revenue share and negative carry-over is that you earn a portion of your players’ losses. But what if they win? Say you have 50 players and they’ve won 10k this month somehow. You earn 0$. And some companies will carry this 10k over to the next month, so you’ll earn 0$ as long as your players haven’t lost 10k or more.
For a long time I believed CPA was better but in the end, it isn’t. The best is revshare in casino / pokerroom / sportsbook with no carry-over.
I thought everyone was like me and would never lose more than 100$, but I was wrong. People constantly play above what they should be playing.
I have sportsbettors which only play for 1$ a day and some others who never lose, so they frustrate me, but in the end the ones that do lose are worth more than the combined CPA of all the players you signed up.