I also have this issue, using CTL-490 tablet is not recognised in system settings, but works fine for the most part. Have been using it with MyPaint and no issues with sensitivity. Only annoying thing is that the buttons on the tablet do not seem to work at all, and I am not certain on how to configure this. But hopefully, when we migrate to Gnome over Unity, this will no longer be an issue.
I also have this issue, using CTL-490 tablet is not recognised in system settings, but works fine for the most part. Have been using it with MyPaint and no issues with sensitivity. Only annoying thing is that the buttons on the tablet do not seem to work at all, and I am not certain on how to configure this. But hopefully, when we migrate to Gnome over Unity, this will no longer be an issue.