dual classing with lowered penalty...
now the whole argument between dual classing and multi is multi levels up slower, but dual has that time until the second class kicks in you are vulnerable and low level, thus easier to kill....
so people recommend you dual early, thus minimizing the "lag time", so you are less exposed until the second class catches up....
but certain kit duals, you NEVER lose some of the special perks....
like the assassin kit, once you reach 9x backstab, thats the max, the engine counts 2 of the multiplier as an affect, the rest is kit definition....
so if you dual to mage, when you reach 9x backstab, you immediately have, even though your assassin abilites are disabled, still have x3 backstab!!!!
big deal you say?
well, if you are high up in assassin class, you get some spike traps, some assassinates, and USE ANY ITEM, and then dual, and now you are a mage, but i think you also keep a ac and thaco bonus, and with use any item, you are NOT restricted to mage weapons, and you still have assassinate with x3 backstab while you dual wield katanas, and believe me this is one evil ability....
you are a mage, so soon you have improved haste and mislead, and you spin into attack, and using assassinate, each hit in dual wielding swords for one round is x3 backstab, you can kill off the worst of the group of enemy.... or use mislead for stealthy approach for special situaltions....backstab over and over...
now this is impossible with cleric dual to mage, or fighter dual to mage, until the second class catches up with first, you cannot use the weapons of the first class....
but with use any item, and that hidden x3 backstab, and a ac bonus, (i have not tried this yet,) you should be at least 3/4 as effective assassin in your mage class, until you catch up....
and lets not even think about poisoned energy blades, and melf....i mean a mage is a pretty powerful class in its own right, so add in the 3/4 power of a high level assassin, and you have just gotten
legally,
the best of dual and multi, the ability to add a good kit, but much less of the vulnerable period when your second class has not caught up with the first class...