Take a look at Kerry Garrison's video of some of the new features in v9:
Looks like some big upgrades including:
-video in 3CX phone
-Now you can attatch mobile number to an extension
-See extension status of remote locations using Call Assistant
-More advanced music on hold (which has been a big request for quite awhile)
-A kind of SLA functionality using call park implemented
-No price increase reported yet
-Call center features did not make it into this version 9 according to Kerry.
-This will be a backup, uninstall and reinstall senario.