Ive never heard of Chase clawing back an offer (or credits like CSR travel credit). Though who knows when that could change (seems like it would be an easy hole to plug). Amex definitely will claw back, but will generally re-apply the offer or credit if a new purchase is made within the time limit (for offers or things like plat hotel credit) - if it is made at same time as cancelation - the existing credit will often just remain