Well,, of course I don't know the details of VST Expression, since I don't run cubase. Only, from what I heard, it never seemed to be a sollution that covers all my needs in a flexible way. Up to this point the enviroment in logic still seems to be the only thing out there to build a template exactly the way I like it. The downside of the enviroment is the hard work you have to put into, to make your template (I am still not finished ... who is?). When I have to do the mentioned 2% out of the system it is not worth it for me. It's always small things in the end you are unhappy with. I am sure I would feel the same way about cubase, after spending a few days with it.
For me it would take a BIG reason to relearn the whole sequencer. Especially, when I have to give up the logic enviroment. CC-editing per voice is quite a great progress (as far as it really works with most of your sounds), but not quite enough to make me switch.
In Logic, I can turn program changes to keyswitches and save all midi-tracks with patch names. That is not as sophisticated as VST expression, but it comes close in my opinion, since I don't really need it to articulations to show in the score.