I have a "sunface" style FF that I made with rather optimal measured germanium transistors though I do not currently have anything built up for a Soul Bender (or Tonebender MK3) to compare.
I would say that as far as the overall quality of the tools of the Bender Fuzz and Face Fuzz in the Fractal product, it is very good and my Fuzz Face was pretty close though my low end was a little looser, actually better in Fractal from that part.
The thing you will miss, if this matters to your playing style, is the clean-up with very slight volume knob tweaks on your guitar when playing on a Fuzz Face style circuit. The Fractal doesn't clean-up like that, so it doesn't do the glassy cleans when you have your knob rolled down low.
However.....there are so many other ways to get that style of touch sensitive playing in the box outside of the fuzz, I'm finding I don't care as much about this one issue. You do get a lot of options to dial in just the amount of fuzz you want in the Fractal, plus the ability to play with EQ and other advanced features.
You could also just run fuzzes in front of the unit. I do, though I'm not really using them as much lately.