I'm trying a tubeless Amerityre All Terrain, but I'd wait before trying it until more feedback is available. I'm having three serious issues so far.
1) The tire got off the rim while I was getting back on the bike path when I had gone on the grass. Luckily, I was going very slow at he time and didn't fall.
edit: bad news, the izip rear rim is bent. The local bike shop said it was good for the trash bin. They said the tire works only a stell rim of a specific dimension, but he didn't know which. I had an aluminum rim. A quick estimate was for $100 for a new rim, installing the spokes and the labor. I declined. My old bike had a steel rim. The Amerityre tire seems to hold to it better. I did the work myself after I straightened my aluminum rim. Took the rims off both wheels and re-installed them on the other spokes. I'll be testing it Monday on my next commute.
2) It seems the tire is slipping on the rim. It completely ripped the rubber band inside the rim that covers the spokes nipples. Now, my rim is untrue. I think the slipping turned the nipples while ridding. I'll have to fix this.
edit: This was because I had an aluminum rim instead of a steel rim. Will test with the steel rim next week. They appear to have one for aluminum rims but it is for narrow widths only.
3) Something is making my bike's motor (and me) work a lot harder. When I let go of the throttle, it slows down as if I'm braking. I'll have to check the free wheel. I know it's not the brakes.
edit: The wheel was so bent, it touched the brake pad in two spots with each revolution. I can't wait to test again when fixed. I really want to have a viable solution for the rear tire flats with this izip bike.
I finished the repairs and took the bike for a small road test today. It feels much more solid now that the tire is in a steel rim. I'll know more on Monday after my first commute on how it reacts on a longer distance.