I'm considering allowing anyone, even Humans, to use 8 points to build their class. That way, a Human Barbarian could, for example, take Fighter 2 and HD 4.
I am also considering letting demi-humans put more than four points in the basic categories. For example, an Elf''s fifth build point can go into HD instead of Elf 1.
The class build system isn’t really meant to be player facing. The GM builds the classes for their campaign using points as a guideline. If players are allowed to just make whatever class they want with it you’re likely to end up with some very broken combinations.
Understood. But I found that players have a lot of fun making their own classes!
I actually think, due to the way XP works, it probably won’t break ACKS too badly.
Remember that each doubling of XP at first level puts a character back a single level (so a Fighter that costs 2,000XP will be one level ahead of a Fighter that costs 4,000XP who will be one-level ahead of a Fighter that costs 8,000XP).
However, if you are to otherwise run the game as-is, it will also make levelling painfully slow.