The legato patch is the only one I used. For mixing, only eq (apart from the reverb of course). Maybe you have an eq-plugin that can "match eqs". This helped me a lot in finding eq settings for the Dimension Strings. I browsed through recordings of a chamber orchestra of my choice to find spots were only one section of the strings is playing. I then used these as reference track, played the same spots with the Dimension Strings and tried to match the sound with eq.
Just for the sake of completeness, here's my reverb setup (maybe that's of little interest to you as you do have MIR):
Independence Origami for early reflections (instrument placement in the room).
Vienna Convolution Reverb Schubert-Saal for the tail.
This new version is on a good way in my opinion. It's less nasal. If you don't mind me saying so, I do like the voicing better in the first version though. I liked how the movement from the first to the second chord was in the middle voices, not the top. In the second version the attention is drawn to the top voice, which maybe isn't what you'd want because it isn't the melody that matters, but the chords. Just personal preference though. Go with what you like better.
I hear what you mean in the middle section, but can't really spot what it is that isn't optimal. Does each section have individual volume curves? It almost sounds a bit too homogenous. Maybe that's part of it.