Agree with much said here - not used ACT that much yet, and not had problems of losing configurations, but do find it a bit hit and miss setting up mappings. Some suggestions for work in ACT:
1. Allow sliders to be configured (for a specific instrument) in "drawbar mode" (i.e. up = off, down = max)
2. Provide a ACT Controller layout designer, so that it can be used on other devices (U-Control UC33)
3. Make the setting up of the mappings easier and more reliable, including clear feedback during setting and also for any controls which might not be mappable
4. Provide more (and more sensible) presets for common VST instruments, or provide a way for users to share these - ability to import/export individual instruments
5. Provide some way to look at (and ideally setup) the mappings maybe in a tabular form as well as the GUI