Well, I gave the Z5 it's first run yesterday and I am happy with it! It was easy to use and the pool looks great. It did spend noticeably more time in the deep end and middle of the pool, but the shallow end got enough attention that it looked good also when the cycle was done. It did miss one little spot where the curve of our shallow end steps meets the side of the pool, making a little 'corner' area, but I think it would be tricky spot for any cleaner because the curve of the steps kind of 'shields' this corner from easy access. And I've only used it once, so I have yet to see if it remains a problem spot. If so, I can just take 5 seconds with the pool brush and quickly swipe that area before the pool cleaner runs. But overall it seemed to work as advertised, and it didn't get stuck on my drain covers, which was a relief. It did a pretty good job climbing also. When it would go all the way up to the waterline tile, it varied how much it would actually move along the tile line before dropping back down. Sometimes it would move laterally across many tiles, and sometimes only a few. This was with the handle set at a gentle diagonal angle, and I think a greater angle setting would make it move faster along the tiles.
All in all, I think this thing is great and I'm glad I bought it!
-Greg