We want to install version 10 trial on top of version 9.1 to see if it fixes some performance problems we are having with backup to USB disks. What will happen if we then decide to go back to version 9.1? Will we be able to reinstall 9.1 without losing settings, will backups made with 10 be readable with 9.1, etc. I've imaged the server, but I can't really backup the USB drives that hold the backups. (I don't like doing this test on a production server, but we don't have spare hardware to do the test any other way. We're also doing duplicate backups to tape with an older but soon to be retired server, so it's not as bad as it could be.)