On some traffic 20% comes out to more. You just have to test it but note you will make significantly less money in the short run. If you need some cash in hand split it up somewhere that will be comfortable. For instance you might start with 80% PPS and 20% going to revshare. Once revshare starts building up you can start moving more traffic through that. Also,
www.bigcashcrew.com has an option that pays some money up front and you still get a percentage.