I've noticed from the Only 6 Pedals topic that the PS pedals are seen by some as an important part of their setup. I'm looking for the BOSS pedal that gives the best artificial double tracking (ADT) sound and up till now, was going to get a HR-2. Should I be having second thoughts??
Depends on what kind of music you play. The MZ2 has a cool "doubling" effect. You could also go with a very short setting on a delay of some sort or a very subtle chorus. The Harmonist is cool but it's tracking isn't always 100% accurate in my experience and it needs to be tweaked for each song in your set list, unless they're all in the same key.
Don't think you'll easily get taht type of sound with the PS-X pedals. They're more useful for things like the solo on "Owner of a lonely heart" or the Brian May type harmonies.
No problem. I hope that works out for you. I've only played with the gain settings a little on the MZ2 and that was quite some time ago, so I'm not exactly sure how well it cleans up at lower gain settings, but if there's somewhere you can try one out before buying it, that would be my recommendation, as they tend to go for over $100 US lately.