I can't comment on the Gyrodec, but a good example of a Zeta I do have currently set up on a restored Thorens TD124.
I think there is some good synergy between the TD124 and the Zeta. currently I'm using a modified DL-103R. (Uwe Ebony body)
I've also tried a Shelter 501-II on the Zeta/Thorens combo. That worked to good effect also. Though the Shelter was/is due for a re-tip (lots of hours on the original elliptical diamond)
I should note that my particular example (Zeta) has been rewired with an Incognito silver harness. iirc, the Incognito kit included silk clad silver wire from vdH. That could be part of my satisfaction.
All in all, if I had to sell one of my tonearms, I'd likely part with the Graham 2.2 before letting go of the Zeta.
What I like about the Zeta is its ability to allow power and dynamics to reach the listener. Yet it is also very good at extracting delicate fine detail. (as might be limited by the DL-103R)
-Steve