Sound PROOFING keeps all the noise you make inside your room. Nothing escapes
Sound TREATMENT is taming all those frequencies that are now bouncing around uncontrollably in your room.

Since  there will be no yearly version changes and this should be the last version, I think this is the best time to upgrade. The new features are worth it, the 3rd party extras are worth it. The fixes, upgrades, new features and tutorials promised and what should be a growing stability makes me think it's a good time to jump on. When new features are added there should be a lot of buzz about it. Sharing ways to use it, things that work things that don't, how to do this or that should be hot topics and and a lot of help. If this really is the last version it's a good time IMHO.  This should be the last version you have to learn.

BassDaddy
This should be the last version you have to learn.

Interesting comment.  In the past, Cakewalk could do some major changes to GUI, workflow, etc. and introduce them with the next version.  People kind of expected they'd have to learn new stuff, sometimes major new stuff.
 
I seems to me that it'll be harder now to introduce a big change right in the middle of a continuously existing version.  Before you could hold back until you were ready to jump.  Now you'll be forced to jump along with everyone else, ready or not.