I have 2 lots of 50 SBD invested. each month I get 1.5 SBD on one and 1.87 SBD on the other (difference due to timing of investments I believe).
My calculations show that 45% APR should be 1.875 SBD / month on 50 SBD, so it's pretty close to the advertised rate. I do not know why the difference, and haven't done any analysis of other investors payments.