1. which is more stable?
2. If you are using the new, why? Seems per the comparison chart that some features were removed, granted they may have been bloat. Looking for understanding.

Only CbB is getting ongoing maintenance and development, so any bugs that are in SONAR are there forever. Fortunately, the last build of SONAR was stable with no showstoppers, so it'll continue to be usable for a long time. Before the BandLab acquisition, continuing with SONAR was my plan and I was completely comfortable with that strategy.
 
Almost no core functionality has been lost in the transition, only a few third-party plugins that Cakewalk had to pay other companies for. It makes sense that you can't give away software for free that contains paid content.
 
As long as SONAR remains installed, you won't lose anything. You'll continue to have access to all the extra goodies that came with SONAR such as Z3ta+ and CA-2A. The only exception that comes to mind is the (non-essential) Pow-r dither algorithms, which were licensed from an outside organization, and which BandLab is working to bring back.
 
You can freely move between SONAR and Cakewalk, working on the same projects in either one. That may change someday, but SONAR has always been extraordinarily good at maintaining backward compatibility (e.g. you can still open 20-year-old projects in the current version).
 
 

I'm using Cake by Band for about the last month. I was bouncing between the two for a long time.  CbB seems to now have everything that Plat had and is very stable on my system.   

Cakewalk. As Dave say, it's the only maintained DAW that I want to use. I don't want to use anything else. I am very familiar with the program and at the same time still learning what it can do.  

2 - Both!  I still need SONAR for projects with 32 bit DX's in for a start.

I have CbB but still using the old Sonar Platinum.  My requirements are small as I use it primarily as a multi-track recorder.  Either one will do.  Old habit I guess.
 
 

I'm using Platinum, only because there is no offline authorization option with CbB, and I don't have internet at my house. Otherwise, I would have updated to CbB on day one.

I do see the Pow-r option in my drop downs.  

Still using SPLAT 2017.10. I'm a "if it ain't broke" kind of guy. Everything works. No issues. I'll switch if I absolutely have to but right now I don't have to.

Still on Platinum. I'll try CbB when absolutely forced but probably not before.