If `BigNameCorp` writes a lot of PHP seriously, you won't notice that many problems. It's not going to be PHP anymore. It's going to be Symfony, Zend, Cake, or something else (maybe even some proprietary, internally used framework). It isn't that easy to find pure-PHP code these days - it just takes too much time to write.

If you do however see an old-style "let's just include everything", "global variables are cool", "just shove it into $_SESSION" kind of code... well - good luck, you'll need it ;)

There's also going to be some forehead slapping as you discover what is not possible (like `function_returning_array()[0]` => syntax error)

I get to write PHP once in a while but normally prefer Python. It's easy to spot in the style of the code written... but otherwise, no problems. I'd just suggest changing the error reporting level to maximum - it's not hard to write a lot of PHP code that will both work correctly and report tens of warnings per line.