Finally managed to upgrade to r508a, a few things I encountered that may help others:
- I had a test program that didn't have a Program.GoBackground() at the end, this caused a massive increase in processor time after upgrading to 508.
Same problem as Peter and Kevin: a clean install of 508 and an import seemed to work well, but I couldn't get my Z-wave to work after this. I tried all available COM ports, Discovery, Heal network but nothing seemed to help. (Upgrading from 506 to 508 didn't cause this problem.)