I actually got a S1 a month ago, that was my learning wheel. I was lucky enough to find a Z10 from a US seller, who got the wheel from China, so I started riding it this week.
What a beast!
At first it took me a few tries to get on (due to the extra weight), and spent 10-15 mins to get familiar with the turns, then I started riding on sidewalk and around the neighborhood. After an hour, I finally started feeling comfortable.
Having the S1 as the first wheel, the Z10 is a different animal. The pickup is so much quicker, and no more beeping at 12mph is a big plus. I feel like the slow turns are not much different than the S1, but I really have to lean hard and commit when I go fast on turns. It definitely requires a different technique but the learning process is also so much fun! Did I say I love this wheel?