But with Plesk you can select what PHP version you want for your website.
You can install PHP 5.3.3, 5.3.10, 5.4, 5.5, 5.5.9 and many more and add it to Plesk for users to decide which version to run.
If something is not working with 5.5, ok switch it to 5.4
I think this feature on Plesk is...