OK so I know some people here probably already know this but I was just doing a little research over the last couple of days. One thing I learned is that the new 9mm P229's are built on the .40/.357 SIG frame. So that means that with a slide conversion and the P229-1 9mm mags there really is no reason why there should be any problems.
So I never heard back from the dude but the 9mm conversion is still on the table( be it a little delayed) at the moment. Still trying to find good deals on the conversion kits. When I do it I will do the slide kit from SIG.