I dont really listen to metal or super fast genres, though there are often faster parts in some of the edm/electronica I listen to. But the Z1R does fine. The DD tweeter is abut as capable as any fast BA, its just a DD so the timbre is a bit different. I personally enjoyed the sound of it with whatever I listened to on it. Heard the M4 briefly but it was a while back and only for a few minutes so I cant comment directly, except to say that for me I definitely still prefered the sound of the Z1R. However, in the bass, its not the quickest. Thats one of the nice things about it, it has a very natural but slower decay with probably the best subbass I have heard in an iem. But I dont think anyone would call its bass quick or fast.
As for the Odin... well, its definitely all hype at this point. Those who have heard it are probably all under NDA, so theres absolutely nothing to go on with them right now. And with how Empire seems comfortable pushing quite unique sound signatures in their high end lineup, based on what I have read about the LX and wraith, I think the Odin could honestly go in any direction at this point. Plus based on the few comments made by empire, I would be very surprised if the price was less than $3k, which at this point is pretty much double your other options.
The Z1R is kind of an anomaly, it has a very unique driver config, and does some things incredibly well, but is certainly not to everyones liking. Again for me though, treble was never an issue. But I can only speak for myself. Fit is up there with the worst I have ever worn though. The custom tips I ended up getting have helped significantly, but its still not what I would call comfortable. A 4-5 hour listening session with them even with the custom tips doesnt sound very pleasant to me.