I'm not sure this is Z wobble so much as Z ribbing. The constrained Z axis with the maker slide makes Z wobble nigh-impossible (assuming your eccentric spacers are tightened correctly). Have you read this article:
http://goo.gl/ci9Gz ?
We have the same Hadron kit from ATI from the same batch and we both have X3's... I have mine set for 16x microstepping (not required, but doesn't hurt). My ZAXIS_STEPS_PER_MM is 2519.68504 (I calculated it then confirmed with a dial indicator). I've only tried printing at .2mm and .4mm so far. For these layer heights I calculated the step-corrected height as .1984375mm for the .2mm target and I just multiply by two for .4mm height (.396875). When I get around to refining further I'll probably get better numbers than this, but at least they should fall closer to step boundaries and avoid the errors that result in ribbing.
If you're still stuck on this you might give this a shot and see how it works for you. My build isn't having any issues like this... mine are more to do with temperature calibration. I spent all day Sunday creating new thermistor tables for my build.
Here's my second or third print. You can see that I don't have the Z issues ... the specs throughout are from temp being too high, as well as the mid back.
-Rick