Does it also emulate some non-linearities/additional harmonics or is it more a "matched EQ curve"?
Well, it has a decent analog saturation algorithm, but as I already said, it isn't an exact copy, so it doesn't exactly emulate the actual frequency response/non-linearities/additional harmonics etc.
it's not holding settings, and it won't take presets, host of fx
I already know about this problem, I'm working on an updated version which fully supports host presets. I will also improve the sound quality and add some additional features. Stay tuned :]