Just tried appmobi. Have to say it looks good. Most parts of my game ran smooth.
Found a few minor bugs, thought this might help.
I use chrome for testing, and I have tested this with the appmobi simulator as well as iOS5.1 (on an iPhone4s).
1> the capx has some ios like scrolling. But appmobi always scrolls to the top left of the layout. You can view the intended implementation working on chrome.
2> text object is not supported on appmobi? I have placed a small text object in the center of the layout.