Waza version of the Metal Zone is honestly really versatile.
By far the stand out feature is the custom mode in my opinion, totally changes the vibe of the pedal from a grunge to a modern distortion, and it sounds great.
If you play on lower distortion it works as just a fuzz pedal really well!
And yes they did tweak the circuit so it sounds good even when not running through the fx loop, even in standard mode.
Overall this pedal isn't just a MT-2 upgrade, but its own different beast. That being said if you are thinking of buying the normal MT-2 buy this one instead, simply a superior pedal being capable of the same, if not better, tones and amazing versatility for only a marginal increase in price.