I just noticed in PC forum that PC also has cash+points reward now. The FTer has come up with a method to buy the points at really low rate through cash+points reveration. You can just make a dummy reservation and cancel it, you will not get your cash back but you will get the full point back. This way, it is equivalent to buying some points from PC at a lower rate.

I am not sure what is the mechanism for SPG. If I choose to pay with point+cash and cancel the reservation, will I get the point and cash back OR I get the points back?