I'm posting this in the hope that someone at PTC will read it. This is the current list of discussions under "Mathcad":
Look at the number of views. "Mathcad 15 compatibility with Windows 8" is closing on 20,000 views. I don't see any discussion about "Mathcad Prime compatibility with Windows 8". I hope that tells you something. Further down, "Where is all the legacy Mathcad stuff (Electronic Books, Add-ons for Mathcad 8, 2000, 2001, 2001i)?" has more than 8000 views. I do believe there is another message there.
No other discussions come close to the number of views these two have.