I have used x16 Media RiDisc CMC-MAG-M01, which work really well with my Sony 710-UL burner, using AnyDVD and CloneDVD2 to do the backup. I would say it is more important that your burner is happy with the media you are using as opposed to the program.
As for burning at that speed I have noticed no problems when watching the backups, and get decent results when I scan the disc. If anything, I only seemed to get problems when I was eperimenting with burning at lowers speeds.
Keep in mind, you only shave a couple of minutes of the actual burn time, when I done a test burn with Nero CDSpeed, I only just reached x16 before the burn ended.