The other "caution" is refare versus rebooking.
Example: refare is where they just lower the fare of your current booking and everything stays put.
For a rebooking, they cancel your current booking and do a whole new one at the new rate; thus all old incentives (OBC, etc..) go away; also, if you'd booked EZ Air, it would be cancelled, and you'd have to rebook at a potentially devastatingly higher price.