Yes, that would be something huge (or maybe I'm thinking that because I have this idea for a long time and really wish someone would do this).
Obviously, the quality of the output php code would matter a lot. Actually, by quality I mean mostly the performance.
I've started something like that a year ago. It's called purplescript( https://github.com/martinrusev/purplescript ) and it's a ruby like language written in Python ( with PLY ) and it compiles directly to PHP, so there is no need to rewrite PHP functions - they just work.
