I find the whole Midi part of Studio One frustrating - I don't understand why when you want to edit Midi in an instrument track, you have to have the "event" selected in the Arranger. And if you want to move on to the next "event" you can't just scroll along in the Edit window. You have to come out of Edit and then click on the "event" in the Arranger, and then go back into Edit. Unless I have missed something.
I rarely if ever have to do that. You can stay in the Edit view, then select the next region to the right. The region is typically grayed out unless selected. If the region isn't visible or readily available to the right (or left), click the W or E key to re scale the view until the desired region (region, being event) is visible). Its all very quick and easy to navigate, actually. There is no need to close the edit window.
If the event to select is on a different track, you can also select the track list from the edit window. I rarely use that method unless I want to select several tracks and show them together in the edit view.
Anyway, give it a try.
Also, sometimes I select certain notes, and try and transpose, and often it moves all the notes in the event - not just the ones selected. So overall, having been used to Midi editing in Opcode Vision and Digital Performer, the Presonus Studio One methodology is frustrating and, to me, a bit unintuitive.
This, I have not ever experienced. Maybe you could show this in a video. What I will see is some notes moving in an event that are just compensating by the GUI rendering. They move visually, only but effectively are not changing. You can verify that by opening the event. But you may be witnessing something else. A video would be helpful for that.
I have started merging all Midi events in a track, but still get issues when I try to edit notes.
If it's a complicated set of Midi editing, I often just export the Midi Events and do them in Digital Performer. It is quicker and easier, there is List Editing and close editing of other track data such as pan and volume events.
I think your just finding Performer easier for your workflow, but I'm not all sure you'd need to.
So it could be me - but am I missing something in Midi editing in Studio One?
Studio One isnt the end all for me either when it comes to the smoothest of editing, but I'm just not going to resort to another DAW, but in some ways, I get your point, particularly with Autoscroll (another subject). It's also possible in my case, that I'm just more critical than I used to be with previous DAW's of note positioning. I'm not a fan of quantization, unless perhaps groove quantize is being used, and even then, I just don't find quantize a musical benefit for my stuff of course.
A lot of note manipulation in Studio One can even be faster than in other DAW's though. For instance, highlight several notes, have the inspector open, and without even clicking on a field, mouse over and the scroll wheel us instantly active to change timing, pitch, or whatever. Other DAW's require clicking on the field first.
BTW, Opcode was also any early sequencer for me as well

. As well as the incredibly brilliant Bill Southworth's Total Music, MIDI Paint, and Jambox/4, which was way ahead of any sequencer layout at the time. Pink Floyd, Herbie Hancock and just a small handful also in on the ground floor of Southworth, thought so, too.
Good stuff.