There is an extremely thorough review up now. Consulting Zini's web site, Zook's design places its external motor below the clitoral arm, not inside it. This is presumably so that the arm will be flexible and fluttery; however, it obviously will come at the expense of direct and intense vibrations.
The Hua is very similar but has its motor located in the arm. I am curious to see how the reviews on that one will pan out.
Personally, based on cool features alone, Zini's prices seem justified. But given that knowledgeable reviewers on this site seem to feel that rabbits are anatomy-specific and can't be designed to satisfy all bodies, I'm figuring I'll wait for sales and reduce my risk of disappointment.