... sort of off-topic reply ... [from "Dietz' Top Secret Production Tricks (nobody really wants to hear)"] [6]
Actually, I use those "warmth"-generating plugins (or hardware) quite a lot, even with our Library. Due to the fact that all our samples are so extremely clean, they can take quite some amount of "distortion" which is perceived by the ear as added "interest" - I had great results with plugs like The Tube, TubeWarmer, Magneto, MacDSP's Analog Channel 1 & 2, or hi-end outboard gear like CraneSongs's HEDD 192.
Especially solo-instruments gain a certain vibrancy from harmonic distortion which makes the performance even more convincing and coherent. But also complete sections benefit from this processing in some context - just yesterday I mixed a dense popsong featuring a large VSL string-section (arranged by one of our EXS-mapping gurus, Christan Kardeis), routed through the HEDD mentioned above, helping the tracks to "cut" through the arrangement more easily.
... and nothing could hinder you from using the real thing, like good old analogue tape, or tube gear ;-]
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... this may not help you in your fact-finding mission concerning Sequioa, but anyway ... :-]
/Dietz - Vienna Symphonic Library