Re: Down tuning with EZII and ZPS
ANY floating bridge HAS to be blocked to change tuning.
The floating works by keeping the same tension between the strings and the springs. If you lower the tension of the strings (Drop tuning), the spring will have more tension, so every string will go sharp to compensate.
Think of it as a "tug of war" between the string and the springs.
I don't have a ZPS, but from what I understand, its primary use is exactly for that, blocking the floating bridge. So, it theory, it should work as well as any tremolo blocker system (from a tremol-no to a block of wood)