Max, thanks for the compliments, and the beer! 
I am not a Notion wonk by any means, although I think the program gets too little credit compared to it's older cousins. It's a terrific program that allows me to get performances from a piece of notation, not just playback. I've done a fair amount of tweaking of the presets, but I haven't written custom rules. I'd like to dig into that but I am curently having too much fun hearing the program perform.
For my strings, I've taken the original Notion presets and replaced the patches with corresponding DImension Strings patches in the VI Pro editor. It's tedious but after a couple of hours work you can replace all the patches. It doesn't really require any coding of the preset rules, just replacement of patch for patch in the VI Pro editor. I then created groups for each of the divisi groups in the string sections.
Reverb is the toughest issue for me. I can't capture that perfect heavenly balance of initial delicacy and detail along with a beautiful rich deep tail that I hear in so many reference recordings. I'm beginning to feel like I'm searching for some sort of unattanable Holy Grail...
Most of the reference recordings that I listen to seem to be set in very deep rich halls. Even small ensembles or quartets that I listen to have the initial delicacy of a close mic but seem to have a very deep rich bloom of reverb tail behind them.
Michael