Rake Share? You mean Revenue Share?
If you are promoting a NDB, you will generally get more players signing up. A lot of freebie and bonus hunters out there. Saying that you will find you will get a lot of sign ups, but few will convert over to a depositing player.
I don’t think a casino is going to give you a CPA on a NDB. And if they do offer it, it would probably be based on the players deposits.
Long term wise, Revshare is worth it. Some affiliates go for CPA because they want start up capital to push their project forward and then switch out to Revshare.