Missing from the list...
Unify's (used to be Siemens) OpenScape and upcoming Project Ansible. I'd be interested to read what you made of that platform, especially the web conferencing facilities it comes with.
Especially with their recent pairing with local suppliers so that you're data always stays in your country and you don't need to invest in installing your own infastructure. Interesting changes afoot.
...and no, I don't work for them, or any reseller for them ... but I'd be interested in another pair of eyes opinion on the system.