"Everyone" know that Apache is for Linux/Unix and on Windows IIS is the way to go.

However, I'm not a pro at Linux and it would be an enormous relief for me to use just the same setup in the production environment that I use during development. I'm a solo developer and I'm trying to make things as simple as possible. I've already got rid of other issues like storage (->cloud) emails (->postmark).

So, what are the real drawbacks that can happen when I just put Apache in Windows virtual private server from Rackspace and use it as the main production environment for a PHP project? Money for more VPS resources is not that big issue compared to the possibility of not having to learn a different OS.

Super-heavy traffic is not expected. Also my PHP project can be quite optimized. There are some heavy scripts, but only for the inside (logged) users. All else can be served more or less statically.