Shade said:Having worked with monster conversions since the inception of 3E, and being around the monster creation boards since that time, I can't imagine this being further from the truth. Adding class levels to a humanoid is ridiculously easy in comparison to trying to update a monster (successfully) to 3E.
Updating a monster to 3E is very easy once one realises that 3E works off very different implied principles to previous editions, and so much of the raw crunch doesn't actually need to be replicated with complete faithfulness. In fact, doing so can often lead to a sub-par monster. What's important is to look at the niche that the monster fills. That can be gaming niche (is it a big brute, an undead bloodsucker, or what), ecological niche (where does it live, what does it need to eat, breed and crap), or dramatic niche (is it going to be mostly a BBEG or a mook, what mythological/fictional sources are you drawing from).
Basically, RAW ogre mage = crappy. Mearlsified ogre mage = awesome.