We already have A band 1 and A band 2, etc.
The strange thing is that the student is never really TOLD what their bands are - maybe this has changed now, but it wasn't the case when I sat my highers in 2006.
The first I knew what bands I got was when I got into uni and they were on the online system. I never received it on my certificates from the SQA, my teachers never told me (apparently the school is informed, but not me?), etc.
So, if it hasn't already been done, then the bands should become more prominent than they are - they should appear on all certificates, and it should be common knowledge that they exist. But they already exist and don't need to be introduced.