Was this an official B&O figure or one being marketed by the guy who made the brackets?
The CD mech itself will work on the bench at 90 degrees but I suspect that problems may be encountered with the CD drawer opening/closing mechanism at anything but flat on a shelf. This is especially so with the mechanisms now not being in their first flush of youth!
The CD mechanism is not actually fixed in the chassis but is free to float on rubber/spring mounts. As the 9500 mounting angle is increased there will be a tendancy for the CD mechanism to "slide" or "lean" towards the front of the chassis and put additional strain on the Door/clamper operating system which may lead to unreliable operation.
Was the figure of 35 degrees suggested in the days of the 9000? This would make slightly more sense as the sliding door mechanism is independent of the disc clamper on these models.
This is merely an opinion based on my experience with a number of 8500/9500/9300 models with unreliable CD door mechanisms. They have to be just right to work in a reliable manner even when flat on a table.