It all depends on your threat model. In the case someone is taking the machine from me while it is off (ie: most theft or legal problems), I have a chance given FDE.

In case someone has physical access to the machine without me around, I have little to no chance, no matter what I do.

A threat model which includes an attacker having potential physical access to a machine to perform an evil maid or other blackbag cryptanalysis is a threat model which is very difficulty to accommodate, and indeed replaced boot files are just the start of your problems.

A threat model without this however, has no reason to necessitate secure boot.

As such, I see no gain in using UEFI or SecureBoot as this guide outlines. It worries me that the author didn't consider a realistic threat model when writing this guide.

This guide also suggests:

> Unless you have concerns about physical security, it is fine to write down your passphrases and keep them in a safe place away from your work desk.

So it's highly confusing what sort of threat model the author had envisioned this to be written for.