You are the reason this compiler exists :) many companies mix the two together. We might be offering commercial support for Phalanger in the next couple of weeks, depending on your company and the project.
Nothing personal but I am sure you understand that we would be pretty nervous about making such a move. There are so many little weird behaviors in PHP that need to be replicated. We have thousands of files and running them would take weeks or months to verify that they still work. Definitely a very risky move.
Absolutely no worries. You can try out whatever you want for free. Several large projects have been built using Phalanger over the years, including Wordpress for instance.