FM allows for tweaks and twists for performance improvements and doing stuff that straightforward-FM cannot do out-of-the-box. At the same time, we should be aware that some of these twists and tweaks will migrate more or less graciously to higher FM releases.
Addendum: for this reason, I prefer employing a plugin for the extra functionality. This gives assurance that someone (the vendor) takes care of issues that may arise in newer FM releases.