Honestly the hassle of dealing with an OTA is not worth it, absent a significant discount. 5x amex points booking with the airline directly is similar value and you won't have a major hassle when you have to cancel or change a ticket.

There is an interesting thread on the UA forum about this right now. UA fare rules are different than AA's so I'm not sure if there would be a similar issue but the short version is that he booked $8800 worth of tickets, watched them drop in price to $2200, and was unable to cancel and rebook and capture the fare difference. $6600 down the drain because he was trying to get 5x pts through the chase portal.