[Bungleau]

All right, let me try to explain this hit point thing again, this time with pictures.

Let's pick a level 12 wizard. He's got... 72 hit points. Now, let's change him into a barbarian.

Wizards average 6 hit points per level. Barbarians average 12. Those numbers may not be accurate, but work with me -- they'll illustrate the point.

New barbarian is level 1. Advances to level 2, and dice are rolled for HP. Comes up 24, which is less than 72 (current HP level). One additional HP.

Advances to level 3. Dice are rolled, total is 36. Less than 73 (new HP level), so plus one HP.

Level 4. Dice are 48. Less than 74 (nwew HP total), so +1.

Level 5. Dice are 60. Less than 75, so plus one HP.

Level 6. Dice are 72. Less than 76, so plus one HP.

Level 7. Dice are 84. More than 77, so plus 7 HP.

Level 8. Dice are 96. More than 84, so plus 12 HP.

Level 9. Dice are 92. Less than 96, so plus 1 HP.

Level 10. Dice are 84. Less than 97, plus 1 HP.

Level 11. Dice are 95. Less than 98, plus 1 HP.

Level 12. Dice are 144. More than 99, so plus 45 HP. Wowza!

Now, I'm probably skipping a few more mathematical steps in here, but that's basically what happens. So when you switch to Barbarian, you don't have to wait until level 13 (in this case) before you start picking up some barbarian-style HP. As happened here, it started at level 7.

So there is a benefit to switching to Barbarian early -- you get the extra HP while going through later classes. It means that you'll advance many more levels with just one extra HP, but that's because you got them earlier.

The same logic also explains why you will occasionally get a skill point when leveling up in a new class, but really get them again when you hit a brand-new level.