You're right, level does have a lot to do with it, and what level you take which class. Some things translate across the epic threshold, but other things, like [LORE]BAB[/LORE] (base attack bonus) do not.As far as [LORE]caster level[/LORE] is concerned, a 20 wiz/ 10 pale master is equal to a 25th level caster. So, yes, spell duration and damage dice will be fine, though a pure wizard will have a slightly longer spell duration, as the pure wizard will have the 30th level caster status. This also means that the pure wizard has a better chance at punching through [LORE]SR[/LORE]. The only other major mechanical difference to note depends entirely on when you take the PM levels. If you take them before level 20, then your PC will gain the benefit of the better BAB Pale Master has to offer. If you take it after 20th, however, you won't gain that benefit, as all characters get the same BAB after 20th level.The wizard would get a few more bonus feats as well, which could ostensibly be used for more epic spells. Really, I wouldn't say that one is more powerful than the other, just that their powers are spread differently. The fact is, all 30th level characters are going to be powerful, especially thanks to magic.
The only other major mechanical difference to note depends entirely on when you take the PM levels. If you take them before level 20, then your PC will gain the benefit of the better BAB Pale Master has to offer. If you take it after 20th, however, you won't gain that benefit, as all characters get the same BAB after 20th level.
Eeek, you're right. I lied. I thought that Pale Masters had a cleric's BAB. My bad. Had to check my own BAB link to LORE, heh.In that case I'm not sure it matters when you take Palemaster, before or after 20th, as it pertains to the 30th level power equivalencies.
You actually have to have the [LORE]wizard[/LORE] levels to get the bonus feats. That is, you can't just take wizard at your 5th character level and get a bonus feat. You actually have to take five, ten, fifteen, etc. levels of wizard to catch the bonus feats wizard's get. Also, those bonus feats only give you access to specific feat options (metamagic, combat casting, etc.), so you can't take power attack with the [LORE]wizard bonus feats[/LORE].