Leaving dread necromancer at lvl 8 isn't as clear cut as k makes it seem. Malisteen on the gitp forums says it better than i can:
"Perfectly reasonable house rules aside, the 8th level dread necromancer ability replaces the entire normal animate dead pool with the new limit. Ie, if you gain additional spellcaster levels outside of Dread necromancer, they won't give any additional control limit, although they'll still let you animate more HD in a single casting, allowing larger minions. In addition, other sources of increased caster level even for a character with only dread necromancer levels will not increase their maximum animate dead control pool, because, again, the 8th level ability does not add to the normal caster-level based limit, it replaces it entirely with a new class-level (which, yes, means levels in that class) based limit. An 8th level dread necromancer doesn't look at caster level at all when figuring maximum pool size for Animate Dead.
It's annoying, but if you max out cha you can kind of ignore it. An 8th level dread necro with maxed out cha has about the same animate dead limit as a 20th level regular caster, barring caster level bonuses, so its not costing you anything if you do only take 8 levels, and that 8th level is still worthwhile for the advanced learning. And the extra HP for your creations isn't bad. And Dread Necro builds can be feat starved to the point of skipping the Corpse Crafter chain entirely, at which point it's a much more meaningful ability. But it's not the magic dump point that K described it as. Ideal dump point actually seems to be 1st (for limitless out of combat healing), 5th (for fear aura), or maybe 7th (for the fancy familiar)."
I would also add that 12th lvl is also a good drop point since that is when you get the choice of 3 very good advanced learning spells: animate dread warrior, aura of terror and revive undead.
