This is probably not that awe-inspiring, but I was rummaging through some things and wound up at the Exalted Arcanist and looked at the wording of the class abilities.
First, their access to the Exalted spell list. It is written for sorcerers, so the spells are added to their list, but they do not get "access" to them, they can only select them. As warmages, beguilers, and the like did not yet exist, it was not written with them in mind, so it contradicts itself for them.
But let us say they get the whole spell list outright the way they should.
Second, and better, is the other 1st level class ability they get. They lose a caster level advancement, but they add 2 spells to their list of known spells. For warmages and such, this is 2 free advanced learnings, with no limits.
So yes, the prestige class requires two less than spectacular metamagic feats, but for certain peculiar builds coming online at 7th level, like a beguiler with back-up blasting, it would work.
Oh, and as a bonus, just to get books thrown at you and you thrown out a window, I checked dread necromancer. They do not have an "ex-dread necromancer" section. So with some extreme chicanery, one could "give up their evil ways", become an exalted arcanist, get all the extra spells, and consecrate and purify his vampiric touch spells all day long. Just to be warped and twisted!