Hi! I know this may be way too soon to ask about this because both of these basses are new in the market but I'm thinking about getting a versatile J/MM 5 strings bass and these check all my boxes.
The Z7 is cheaper but more versatile with the 3 band preamp with mid frequency selector. It has the specs closer to a MusicMan bass and even the J pickup is closer to the neck like they usually do in MM basses. The humbucker seems to be placed a bit further from the bridge, which I also prefer. The only downsides that I see is probably the weight, the fact that it doesn't have passive/active option nor tone control like the other Sire models, the J pickup too close to the neck for my taste and probably the neck profile compared to the Sadowsky.
The Sadowsky is lighter and I love the neck profile of their basses. The j pickup is in my prefered position. Also, both pickups can be set to single-coil, parallel and series, and it can function in passive or active modes. The downsides are the preamp that is more limited compared to the Z7 because it's a two band boost only without the VCT, and also it's more expensive. But honestly, much of the MM tone is from boosting bass and treble, so the preamp wouldn't be much of a problem.
I think that the pickup's switches make the Sadowsky a very versatile bass but the Z7 also offers so much at a better price.
It all comes down to tone. And from what I've been hearing in the few youtube videos available, the Z7 is closer to a real MM bass while the Sad seems to be a bit more of a hybrid bass that has that MM quality but is a bit diferent.
Has anyone had the opportunity to check any or both of these basses? What are your thoughts about them?
EDIT: It seems that the Z7 has active/passive option as well.