We have a couple of Polycom CX5000s too - the second one we had to source from eBay! We use Skype for Business for 100% of our voice and video communication, and have virtually no trouble with it.
Any problems in my experience stem from remote users' ISP bandwidth issues, or their inability to read instructions. No complaints about SfB.
I wonder if the author is using Skype for Business or the consumer Skype.