I heard both speakers at the audio show in LA earlier this month. It's really hard to compare them both, especially given the different rooms, electronics (Zu had much more modest source and preamp on hand relative to the Wilson room) and short listening session. I really liked both and am guessing the Zus are much better bang for the buck. However, I did find that the Zu Definitions did not provide a presence at the bottom-end to match the Wilsons. the Zus excelled well in other areas but didn't have the presence of the Wilsons.
Watt Puppy 8 vs. Zu Definition
There is quite a heated debate here on both of these loudspeakers. While I much prefer the build quality and appearance of the Wilson's, I want to comments on the absolute sound quality between the two. Please comment only if you have actually heard both of these speakers and tell me which one you think ultimately sounds more musical.