I haven't owned a Metal Zone for at least a couple decades and was never able to get what I considered to be a good sound out of it, so I chose the last option.
I had one for a while and couldn't really make it work for the stuff I like to play. There are a few sounds in there that I'd call decent, but the controls were so finicky that it was near impossible to get exactly to what I liked at a later date. I could see how it might be great for a very particular kind of guitarist.
It's best used into a super clean amp, possibly as a pre-amp strait into the power section. And the eq for the midrange has a pretty wide range of settings. Set it with your ears, not your eyes.