Johannes Schlüter has a post to his site detailing the handling of types in PHP and MySQL and how they might act differently than expected in some situations.

Since PHP 7.0 has been released there's more attention on scalar types. Keeping types for data from within your application is relatively simple. But when talking to external systems, like a database things aren't always as one eventually might initially expect.

He talks about MySQL types and how they relate to the "network protocol" being used, converting everything to strings. He includes a few examples of hinting on the results, one where an integer is expected/string provided and another where a string was type hinted but an integer was returned. He points out that sometimes this is a limitation of what PHP can handle, not always what MySQL returns. He also includes other examples of returning decimals - sometimes as a number value and others as a string.

This leaves the question whether you should disable the emulation in order to get the correct types. Doing this has some impact on performance characteristics: With native prepared statements there will be a client-server round-trip during the prepare and another round-trip for the execute.