Saturators are cool thing, but demoing lot's of them kind of throws you into unknown water as you (probably) don't know how tape/gear/tubes and such should sound. We, who were lucky enough to live part of childhood with tape records have at least little hint. (I believe kids of 1992 and more may not even remember old MC tapes, wallkmans and such. :D) Lot's of saturatos came close in my demoing madness time, but best I've tried was VintageWarmer, Ferric and Ferox. (Didn't try all of them though.)
Now, I find one problem with saturatos, it's low end response. They add so many harmonicss that low end just becomes less and less vivid. (Painfull on kick track...)
VintageWarmer solved it by internal multiband processing, but firstly it's expansive as hell and secondly the flavour it brings into the signall is so intensive that it can mudd your mids really quickly while mixing. It also wiedens stereo image quite heavily, which can kill all your efforts in that area.
At the first sight, Ferox seems like it suffers from that harmonics problem too, but it's trick is in output volume. Other saturators add harmonics, so sound gets ritcher, but louder also. If you notice you'r lowend's suffering, you can't do much about it. Ferox, somehow, doesn't. It's output goes even slightly down as you saturate more. That means, that it seems like you've lost some of your low end, but when you compensate that volume loss back, you've got nicely fat sound with good low presence again. (Great on kicks and bass! ...when not overdone.)
Also sound is nicely clean. It reminds me my old MC tape listening times even bit more than VintageWarmer. It's actually similar to Ferric, but it can go harder, not so subtle. Roolls off highend by 1 or 2 db btw, but I found this less and less surprising. Even VW solved this hardway ... by adding EQ. :D
EDIT: It's single band, so it is still better for individual tracks instead of master. But usable too. I'm not into bussing that much so can't report anything about buss behaviour.
Those are my first impressions and again, there is "yeeeeeyyyy" effect that may couse me to overreact, but right now, 10 fo sho... :)