In my opinion, these skills are great for spell-casters. Sure, "mind-focus" is clearly better then skills such as "sorcery," however think of it instead as an additive skill. First you take "mind focus," then afterwards you take "sorcery" and the like. It's similar to combat skills in this respect - people have their favorit skill that they always teach the primary melee combatants first, and afterwards they load up on the other melee-oriented skills.
In my mind, something like "mind focus" is fine due to the relatively low number of spell-casters in the game and the fact that it's only one skill - beyond that there's only the standard academic skills to build upon.
Personally, I would recommend allowing this skill set to increase the efficacy of magic-users, which will add to the variety and flavor of the campaign overall, rather than limitting an already somewhat limited class of characthers.