Your first post made it seem as though you had not yet installed ICS on your Xoom, but were simply questioning what advantages you would receive if you did. Is that correct?
However, in your follow-up, especially in noting those things which were working, but now do not, it would seem as though you DID install ICS, and have found these issues afterward.
For clarity, and so that others might be better able to address the issues you are having (and this would go for anyone else as well), it's always a good idea to include pertinent information including if your Xoom is WiFi-only, LTE, or even still 3G; as well as the information about source and build if you have installed ICS.
The semi-official 'Soak Test" version (for WiFI) is not the same ICS as the CM versions. If you received the upgrade as part of the "Soak Testing" you need to let Motorola (I believe it's Moto you would report these too, and I assume they informed testers how to do so?) about these issues so that they will know what they need to address in subsequent revisions.