I flew at FL90 up the valley SPR-FRI-WIL about 10 days ago, IFR in VMC. The impression I got from that was that it was Class E airspace and there was a lot of uncontrolled VFR traffic about. Bern was quiet and relaxed, I doubt transit would be a problem at that level. I don't know how that would change as you approach Zuerich.
The view is, of course, stunning.