I think it's going to take me a few weeks to learn and evaluate how well it works with the orchestral libraries. If you still want to hear about it then let me know.
Preliminarily this is where I am at..
The way the ROLI's work is they record the strike/velocity of a key just like a normal keyboard, though the feel is different naturally, but also have a side to side finger slide which is sent as a pitch bend wheel MIDI message, and then an up down finger slide (up and down the key), which I can't get to work with Kontakt yet and have asked ROLI for help about how it works -- no reply yet. There's also the recording of the upwards release of the key, that I haven't fiddled with yet either in Kontakt and am unsure of how to utilize even when working, and aftertouch, which is basically a continuation of holding the key down more lightly or heavily as you please, I can get that to work in Kontakt and has its uses when tied to volume level in some cases. I think I'll be using that ability a decent amount in future.
Trying to get all of the ROLI to work with Kontakt is teaching me a lot more about Kontakt. I have mainly only used it in the past as an engine to run plugins, and not used it to tinker with sounds much at all.
Some orchestral bits work well with using pitch bend as vibrato, some don't, I think the strings tend to more. It's less of a realistic vibrato however to use the finger pitch bend rapidly back and forth than the built in recorded vibrato of a sample library. So it may be not be the best path with a realistic library or realistic music. I'd like to tie vibrato to the finger slide up and down motion, and that'll be great when I can set it up, but some libraries don't have a blend in vibrato ability, you can only key switch to it, so forget it.
The most fun I have with it is with the CS-80 V which is made for poly aftertouch after all in the first place. I haven't used Equator enough yet to evaluate the ROLI thoroughly either, I've only had it a couple of days, but my impression is Equator could use a lot more sounds than it comes with. If I used Noise I'd probably feel more fulfilled built-in sound wise.
To sum up at this point, after getting the ROLI, I am still picking up how to get it to work with Kontakt fully, and evaluating each of my library's samples to see how much they can be integrated with it. I had one test where I tried to set up multi track poly aftertouch with one of my orchestral libraries and it was too much for my rather high end system to handle and I just got distortion, so there're a lot of factors as to whether you can set up a ROLI to work fully with one library or another.