Welcome Viktor,
I’m going to give you an answer based on my own 9 years of experience in this industry… that doesn’t mean I’m right but hopefully might give you some prospect.
So… on my case, I basically never go for CPA, no matter what the industry is.
Even if I can get only 10 players in a certain month, chances are that I might get 1 player that will spend some and perhaps even will keep on coming back every month give spend some. I’m on the gambling industry, I figure that I should be my profits too. Sharing is higher risk but often higher profit in the long run.
In other words, if you don’t want to take any risk, CPA is the way to go and with time you learn better how much your traffic is worth.
If you don’t mind taking risks of getting nothing some times, profit sharing is the best… on my opinion. 