In reply to Nick.

RE: PHP vs. Twig, I've used Twig within ACF blocks, often in conjunction with the Timber plugin. The PHP file that is used to display the block just needs to gather the data for the Twig template and then render it. It adds a bit more complexity (and two files, a PHP and a Twig, per block) but as Twig is pretty easy for folx to mess with, it's been a good solution for me.