I believe the reason they won't do PM is that after MIR, the price will be already lower than outpost.
Actually, at first I didn't mentioned MIR, and the CSR did agree to PM for me, but when I mentioned the MIR, she refused to give me PM.
So I guess if we don't mention MIR, CSR may PM it. But the question is: the MIR is also provided by Staples, so their MIR department may find the trick from the receipt together with rebate form, and probably they won't give you the rebate. Any comments about this?