We switched our studio from Corona to Moai last week. Corona is good for beginners learning Lua but has significant performance limitations that we could not overcome. It took me a week to port our Lua code over and write an extra management layer but overall we are much happier with an open source platform like Moai. I had a couple of questions on Moai which were answered promptly in their forums.
What finally pushed me over the edge was the Moai game Crimson Pirates which was #1 last week. See this video and download the game to see what I mean by performance in Moai. You couldn't write a game like that in Corona and get good performance.
Not sure if the Corona/Flash connection is a good thing. Flash may be popular but it's held in very low esteem by most game developers. When I challenged Walter on the performance issue, he didn't have any good answers. At least with Moai if I don't like the performance I can look at the code myself.