I understand how it can be a wrinkle. There's always the Axe-Fx III but that's a different price range and form factor. Practically speaking, I think for the TS type of case, you can use some EQ to emulate the lower impedance. And for the fuzz case, no fuzz nut really seems to love any fuzzes in any digital effects boxes anyway, whether it be in the HX, Fractal, etc. It seems to me people who really want authentic fuzzes will use fuzz pedals, variable impedance or not.