I've actually got quite far on that project, though I'm not sure how everyone else will like the balance levels I've chosen. I'll try to speed progress and make a version to share.
I don't think removing the low-level mages is necessary - I just simply made the level-1 spells apprentice-level effects, the level-2 journeyman/hedge-wizard-level effects, etc. I just wish the maximum spell requirement weren't level 9 in two paths, because Dominions really has a broader spectrum of power levels, especially when magic booster items can be used. But so far I am pretty happy. There are just so many spells and items that it takes a long time to do them all and keep them consistent. And nation balance is of course all shuffled around by this, but that's interesting too...
