I flew a OW biz rtw award last summer. I used the one allowed open jaw. I was told we could not change the routing once ticketed. Never tried to do this.

On some segments had to fly coach because no biz seats available. Was told that if a biz award seat became available, I'd have to pay $75 change fee. As it turned out, I was never asked to pay the fee on the two segments I did change to biz.

For me, biggest challenge in planning had to do with restriction of flying in and out of a particular city only twice.