Personnaly I like the error printed in the book (each magical adept talent increases the burn-resistance by +1). I also intend on making spellcasting level = spell level + number of magical adept talents. In fact it would seem making the guy as powerful as a normal D&D wizard, but it won't be always the case. A 7th level Smart hero with 4 magical adept talents could cast a fireball at 7th level (with that houserule), but a magic-missile at 5th level (weaker).
Also (with the book's error), a 7th level Smart hero with 4 magical adept talents and Int 16, who would cast the same number of spell levels as a basic wizard, would statistically lose only 4 points of Strength during the day. Thus he could cast more spells if need be. After having played for years with a spell-points system that entitled more lower-level spells per day (cast as a sorcerer) it wouldn't unbalance the game IMO. Also note that he must succeed a spellcasting roll, which makes his magic less reliable. Of course, without the errata for the magical adept talent, you don't play "low magic", but I also think you neither play munchkin magic. Using the magical-adept talent as printed I thought about the following ideas:
- Preserver / Defiler. Using Grim Tales for Dark Sun (or similar idea), the defiler uses the magical adept talent as written in the book, while the preserver uses the errata's magical adept talent.
- Moorcock's world of Law & Chaos. In area where Chaos is stronger, magic is stronger, while in areas where Law is stronger, magic becomes increasingly difficult to cast. So, strong Chaos = magical adept talent as written in the book; less Chaos and more Law, magic is at -1, -2, -3 penalty etc. as relevant, where penalty equal number of magical adept talents "temporarily removed" while in the zone (so casting level decreases, and spell burn increases).
- Ley Lines and similar stuff. This is a world where magic is stronger near "ley lines" (or other sorts of high magic zones, such as near a gate for example), and weaker everywhere else. So, near ley lines / in high magic zone = magical adept talent as written in the book; everywhere else = errata's magical adept talent.
Having magic that work always the same everywhere, is also a staple of D&D, and that also could be changed when playing Grim Tales. Magic would become all the more mysterious and unreliable, thus all the more magical IMO. A world like that could be at the same time low magic and high magic, depending on the circumstances.