You are counting the same $300 twice. Once to reduce the annual fee, and again to claim that you are receiving a free month's hangar rent. It's one or the other, but not both.
Good point! Either way, the $300 travel credit matters and it makes the CSR card a lot more attractive.
Since I PC'd from the CSP to the CSR card when Chase announced the new rules, my calendar year anniversary is in December, the month I originally got the CSP. So I should get $300 now and $300 in December (I think)!