There was a recent thread from a person that wanted to downgrade their version of Sonar to a "lower" version.  Correct me if I'm wrong but the only real difference is the add-ons that come, or don't come, with a version (in most cases).  Thus "downgrading" because you don't like an add-on that came with a version seems misguided.  Plus, if you don't like a certain add-on just don't use it.
 
 

I think the reason for that other thread was different:
the user has not found any value in Pro compare to Artist, with extended explanation why (some points was questionable, but in general everything was valid). He is on monthly membership for a half an year (according to its forum registration date), so he has practically payed more then Artist complete price. And he has understood that Artist has everything he needs (and what is not there is also not in Prod version). And so he asked either he just can get Artist already or at least stop paying for Prod and continue with Artist.
 

fireberd
Thus "downgrading" because you don't like an add-on that came with a version seems misguided.  Plus, if you don't like a certain add-on just don't use it.

That is only valid in case you do not pay extra for that. Not the case with Sonar and current price politic.
 
Since users can not really answer on that question, the thread went its own way