A lot of fuzz demos will sound fizzy if they are recorded direct or with a cab with a tweeter. You can bet that all of these crazier fuzzes will sound pretty fizzy, but that's something you fix by using a tweeterless cab or cab sim!
I didn't rate the Megalith when I tried it, it sounded too spluttery with no body to it unless you scooped all the mids out. I've tried a lot of fuzzes and often struggled to match the tones I've heard in demos though, which I think is due to using a high output passive bass (Yamaha BB1025X). Since getting a passive Jazz with a brighter quieter sound, I've noticed how different some pedals can react, so my opinion of some might change if I had the chance to revisit them.
That Pale Mare clip sounded great, although I'm not sure they're currently available?