First, I will agree with the OP that Sonar has plenty of MIDI bugs and things that just don't work right. I really hope Sonar works on some of the MIDI features, particularly the step sequencer and programming drums.
I work 90% with MIDI and VSTi's, but I'm not a composer so I only will have 6-8 tracks usually and not a ton of plugins. I don't use advanced MIDI features. As much as new features are cool, I'd prefer they spend more time on bugs and enhancing existing features.
However, I've also tried Studio One 2, Studio One 3, Reaper and Cubase repeatedly. I've actually spent more time demoing new toys and switching DAWs and plugins than actually creating music, which is why I decided to reformat, bought lifetime updates, installed only the SONAR stock plugins and Komplete 10 (which I also own), and refuse to install anything else. I need to learn to use what I have to its full capabilities, which will take years as-is! I find the Lifetime Updates to be a relief. . . now I'm committed to a DAW and I don't have to worry about paying more to upgrade to the next version. It simplifies my life.
Other DAW's will always look shiny and better, particularly when watching videos or reading reviews online. Their features seem awesome and super useful when I watch a pro using them in a video. I watch Hans Zimmer use Cubase and it seems like I could do the same thing if I just had Cubase!
However, like all things in life, most of it is just advertising and the fantasy that this new software is going to revolutionize your music making (and life) for the better. Once you start using them, you start to notice the bugs and things that don't work right. They all have them.
After trying out other DAW's repeatedly, I always came back to Sonar because it provided the best mix of features for me.
I say this only to give you some food for thought. It sounds like you're an advanced user and you've used Sonar for a long time, so it may be the right choice for you to change. But make sure you separate the marketing hype from reality when you decide!