Oh, so there are a lot of stuff here to respond to. I 'll try the order in which they appear:
I really don’t want to give shopping advise, but consider this: if you are set on MG3 as your preferred software (once it is being released), wouldn’t it feel superfluous to have a Jamstik on top of that. There is really no gain other than satisfying a purchase itch right now. The Seaboard of the other hand, you can use as acomplemet in your setup. It Is also a fact that you are going to be able to play stuff you can’t play on MIDI Guitar with that. Pressing down on chord notes with varying degree of force, for instance.
Well, what platform are you on? This MINIMAL version was released a while ago for Mac, ad it has at least some partial MPE support:
Yes, I have a few videos on the subject, and all involves the GP-10 as the way to go. But first, this has nothing to do with MPE, really. Sure, it gives you a chance to bend strings within chord in a similar manner, but that is it. It is a way of approaching what the Fishman triple play offers in a way.
there are a few different approaches to filter notes like that. MIDI Guitar has some pretty good solutions in the MIDI Machines. Other than that, I use Abelton for rack splitting (keyboard mapping), and I am sure there are similar ways to solve that in Cubase, if that is what you prefer.
