Ok, so given that my 48-month window of ineligibility for a new Sapphire bonus ends in about 3 weeks, maybe my best move is to downgrade the CSR to a Freedom now, to avoid the Nov 1 annual fee hit, and then wait three weeks to apply for the CSP, hoping that the signup bonus lasts that long.

The risk would be if Chase decides to change their rules on converting UR points during that three week window when I only have a Freedom and no Sapphire card. Seems pretty unlikely.

And then I'm still a bit concerned about what downgrading the CSR means for travel insurance/purchase protection on the fairly expensive trip I booked late last year with the card.