In my 2 1/2 years or so journey with Studio One(since S13 release) since I jumped ship from SONAR Platinum, I have found that Studio One is capable of quite a bit more than the user manual would suggest, the manual is not the best, it gets you off and running if you need it, but it needs to have more depth put into it.
As far as Midi goes it's the same, there is more than meets the eye, not as much as some other DAWs there is no doubt. Whether it is deep enough for a persons use depends on what they use it for, what they need. For me it does everything I need and more, but I'm not deeply involved in the Midi side apart from programing drums, keyboards/synths etc (all in the box). But for others such as Tenfoot who's use goes beyond that, it may be seen as lacking, and it is no secret, most people know and will admit that while being more than sufficient for one groups use, it comes in short for others, that's just how it is at this moment in time.
For me and my use, there is nothing I can't do in Studio One that I want or need to do, there is nothing I miss from SONAR, but there would be a lot I would miss from Studio One, for others it may be the other way around, again that's just how it is.
With SONAR, the fact is it is dead, it's gone as far as it is going to go, forum member SimpleManZ made a comment which is very true and worthy of thought
To me what is most important, is not what Sonar does but what it cannot do.
And cannot do is the future. (SimpleManZ)