There is more about midi than its DAW midi features. I have been with Studio One for 7 years now and using its midi with a fairly powerful external hardware based setup. I have got up to 10 hardware devices I can run in tandem with the DAW audio/soft synth side. The hardware still sounds rather excellent and sublime in tandem with the audio quality of your DAW and the sound of its internal soft synths.
Midi timing is very cool in Studio One. I run a midi interface on its own USB port that is on a card plugged into a PCIe slot. So its independent of everything else. Its 8 midi ports connect to my 8 main synths.
Sonar's midi timing to me feels like it changes when the audio side of the program is working super hard.
(e.g. CPU resources being pushed) I maybe wrong but I always found that the midi timing was somehow linked to what the audio is up to. When pushed super hard, it seemed to change.
Studio One is solid and tight no matter what the audio side of the system is up to. It locks into the metronome real nice here. All parts. All my synths are on channel 1 and on each on their own port. Often I am only getting one sound per synth as well. This all rocks super nice for me. Latency is super fast like this. 1mS or so! per instrument.
You can do some tricks too like put Studio One into record, setup a loop and loop and jump midi tracks on the fly. Adding in new data just for that track. The synths will respond according to what track you land on. For me this was the main reason I switched. The gapless engine comes into play rather nicely when working with lots of hardware synths. You can do multiple things while Studio One is in record or play. When you land on a track you can jump out of record and rehearse, jump back into record and then add in new material. Sonar cannot even attempt this. Cubase and Logic would be able to do it though.
The internal midi resolution is super high. Recording and playing back really well and beautifully played non quantised parts with great accuracy is one thing Studio One does very well. Advancing midi tracks timing wise by fine tuning is super easy and any latency due to when the sound hits its peak in terms of the grid can be compensated for very well.
There are a ton of existing midi operations the can be performed on your recorded data. More than what you actually need most of the time. The Studio One midi editing and features all allow one to create a great sounding piece of music and in the end that is all that really counts. It is missing some advanced features, but all the midi basics are there and they are solid. The PRV view is beautiful and perfectly fine. You can see note velocities and control data all at once. You can edit multiple midi tracks at once. Automating midi data is a breeze too. Future updates may add in more features. V4 is on the horizon and you can bet it will add in some nice things.
You can add in plugins like the free Cockos Rea stuff. One of those free plugs is a midi librarian and can act as a library for any synth. Sounds can be auditioned and loaded in and received back. It is handling SYSEX data for you and runs inside Studio One. Midi preset definitions can be setup as well. Its also free. Midi editing features can also be bought and plugged into Studio One via plugins. They have started creating their own with their existing 4 midi effects. Incredible step sequencers can be added too. Build in the areas you need.