In original PS:T as well as the current unmodded EE version, it matters which class you gain a level in first. A Nameless One fighter gets a max of 10 hitpoints per level, a mage gets 4. This...:
1. Contradicts the manual:
The Nameless One only gains hit points when he gains a level in a class that’s higher
than the maximum level he’s achieved in any of his other classes. For example, he
starts off as a level three fighter and a level one mage and thief. When he gains
enough experience to become a second level mage he won’t get any more hit points
because his mage level (two) is still lower or equal to his fighter level (three). When
the Nameless One gains an experience level higher than three, then he’ll start to
accrue more hit points (always 1-10 hit points per level).
2. Adds an excessive metagaming aspect.
If you want to maximise your HP, the optimal thing to do is to watch carefully which class you level up first, not just for levels 7 and 12 where you get the specialisations, but at all times. That's just silly. You also need to level up all classes, because you get extra hitpoints for that as well.
It should be possible to care about maximising the power of your character, and still JUST play the game in your favourite class.
It's important to understand that this is not a case of "well, if you wanna play a mage, you'll have fewer hitpoints, that's how the class works". Because the TNO isn't like a normal character that commits to a class, with all its pros and cons. You can have a TNO who is at the same time a level 18 fighter and level 18 mage, and with vastly different hitpoints depending on which class you levelled up first.
You could say PS:T is for story and isn't for powergaming, but the EE base game itself contains the "max hitpoint per level" tweak precisely so that people wouldn't feel the need to reload to not feel cheated out of hitpoints, so clearly the game already tries to acknowledge that people feel that way.
This was fixed by the Fixpack, but apparently EE didn't implement this fix. My question: is that a simple omission or is there a reason for it?
Whichever it was, I'd be good to see it changed to what the manual tells us.