In the midst of all this Windows 10 confusion, the question came up - should I upgrade from Sonar Studio X3 to Sonar Professional ?  Might be able to do it for $75 on a good day.   I haven't found anything specific on this...  Can anyone tell me the main differences, even in general terms ?  Is it a subtle improvement or night and day?

I went from X3 Studio to Platinum with lifetime updates and I am so glad I did, yes, much more stable, unbelievable
amounts of new shiny bells and whistles that I can't imagine doing without now... love the Theme Editor, others on the forum are making stunning Themes for everyone... there is just a lot of reasons to go up, I wasn't going to, but now I am glad I did... It is well worth it

Night and day...
become a lifer... unless your just playin' around.

X3 was such an improvement over X2 it's become the "Windows XP" of Cakewalk, where people stay on it because it's so much better than what came before. But what SONAR can do these days is indeed night and day. It's kind of like when you drive a sedan - it works, and gets you where you need to go. But then you drive a sports car, and find out that driving can be fun. 

yeah upgrade to platinum

sheesh...   the platinum upgrade is $299 from studio.  I was just going to go for the Professional upgrade at $99.  But then one year of updates is another $99.   I've been doing "ok" without any updates on my X3e studio...   and don't know the advantages of getting updates anyways.  Really not into spending the $299...     so many other areas to spend money on, you know...    what will I really be getting in terms of real benefit if I bite the bullet and spend the additional $200 for the Platinum version?

AD2.

Chevy
sheesh...   the platinum upgrade is $299 from studio.  I was just going to go for the Professional upgrade at $99.  But then one year of updates is another $99.   I've been doing "ok" without any updates on my X3e studio...   and don't know the advantages of getting updates anyways.  Really not into spending the $299...     so many other areas to spend money on, you know...    what will I really be getting in terms of real benefit if I bite the bullet and spend the additional $200 for the Platinum version?

Fly Out Zoom EQ with analyser.  More pro-channel plugins.  Mastering Plugins, MOre AD2 kits and midi packs, Drum Replacer, Soft the AAS synths, full versions of Dimention and Rapture, TruePianos, Vocal Sync
 
LIFETIME UPDATES!!!!

Chevy
what will I really be getting in terms of real benefit if I bite the bullet and spend the additional $200 for the Platinum version?

A whole different DAW.
A state of the Art tool designed for recording. I was pleasantly happy with X3.
but now that I've used Platinum, I could never go back to using X3. I'd be lost.
and its not just the cool colors. its the tools.

Hmmm..  ok you got me considering Platinum now...  when you're passing out nickels like they were manhole covers, it's kinda tough... was even considering jumping ship to another DAW due to the cost of the upgrade. 
 
Anyways, 2 things that really bugged me about Studio X3...  and please correct me if I've overlooked or done something dufus, which may be totally possible... I tend to just skip and ignore things that don't "work" for me right away...
1) the way that Prochannel was employed... you'd have your 3rd party plugins shown clearly in the FX Rack in the Track View, all visible right there (which is great), but the Prochannel plugins weren't visible there. This was hugely annoying, so I didn't even use them.
2) the console view, unlike many other DAW's, displayed only I think 4   3rd party plugins, and then you had to scroll to see the rest of them....  again hugely stupid and annoying.  There's plenty of space in the console view to list 10 or 12 plugins if you had that many. but they chose otherwise. 
 
I think #2 is addressed in the newer Sonars...?, but don't know about #1. 
 
Anyhow, I do hugely appreciate your input.  Thank you!  I have a hell of a lot to learn, and avoiding financial and time investment blunders is super important.