Login to your amazon affiliates from the US, the % is almost double. Starts at 4%, make 7 sales goto 6%, then make 14 sales goes to 8% (i think), never had sales go over the 8% bracket but they def get more in the medium to long term.
Edit: I have noticed tracking issues with Awin (on content blocks at least), I have sent friends and family to my aff sites to buy and they have bought but the comms not been registered so I'm moving away from awin more and more as the odd missed comm I can live with, but multiple is taking the mick.