Earlier I was looking at some of the low BizFirst fares to Europe on CO (Z fares). They also come with a $400 change fee. You'd really get hosed booking one of these. Once the sale is over, you're likely to see another grand or more in fare difference plus $400.

One trick with awards, particularly those booked in advance, is to wait until the last minute to cancel (not always possible if you need to rebook right away). If the carrier changes its change you can usually cancel & redeposit for free if the change is unacceptable to you.