I've only used their WavePad Audio Editor, (IIRC, they had a free version but I can't seem to find it - maybe it's the default if you don't purchase), so my experience is limited to:
1) Installed it, saying No to any optional extras.
2) It installed a load of extra shortcuts for their software - that's OK, it put them all under one menu item, not spread all over the place.
3) Copy WavePad Audio Editor executable elsewhere and uninstall it - it works fine as a portable app, (even though I don't use it anymore).
I've never received any email from them in over 12+ months.
Anyway, not what you probably want to hear but just my limited dealings with them.