Running Multiple Magic Systems

I’m considering putting together a storyline where different cultures utilize different forms of magic.
Possibly allowing the elder races the use of Art Magic where as the younger races would use Sorcery and Abstractions.
The Magic Burner advises against mixing systems, is it a game breaker to do so? Is it just ill advised? Are there some pitfalls and problems that could arise that I should consider before going ahead?
Or is this just a really really bad idea?
(The campaign idea is finding a lost empire that still thrives and remains true to the old ways)

The general rule of thumb is that Sorcery= (standard) Sorcery OR Art Magic OR Practical Magic; plus:
*Spirit Binding
*Death Art

The add-ons can be added to represent arcane and exotic sub-schools that are represented in the lifepaths. Faith of course is its own strange domain that mortals can only ponder at. I would recommend against using all of them in a game; use only what your narrative demands. The human brain can only handle so much math. Maybe write a short narrative, maybe a bullet point or two, about who uses what type of magic, and only use what’s appropriate to the story.

The idea is for an elder race whose magical abilities our different from the sorcery of the normal world. The elder race wouldn’t be able to use standard and the standard race wouldn’t be able to learn theirs (Art?). Kind of the way that elves and humans have their own systems of magic.
Note: I am open to other suggestions on how to represent this as I am only in the starting phase of this project so nothing is set in stone.

Using Practical Magic and Art Magic together worked okay for me as long as no single person could know both. I don’t want to do it again but there’s nothing wrong with it.

However, if you want an elder race whose magic differs, don’t use sorcery. Elves already have their own magic in spell songs. Just give them more spell songs doing whatever it is you think Elves need to do. Art Magic’s flexibility is already a huge benefit; Elves with Art Magic are going to be ridiculous. Having one in a group will probably lead to feelings of unpleasant power imbalance. If there are no Elves in the party it’s a lesser concern, but I’d still recommend having Elves use songs to do their thing.

I was going for a human like elder race, one that would appear to be more like an evolutionary stepping stone between mer and man (and an unknown danger to both)…
I suppose I could burn up a race of with their own natural or emotional magic attribute that would eventually drive them into a warlike rage (combine the effects of grief and greed so that when one of the elder race hits D10 (Attribute) they take to the field with whatever forces they possess to conquer whomever they may (leaders wage war, individuals go on killing sprees, suicide missions, become adventurers, ect). They would outwardly appear to be a peace loving race however this would only be the discipline they use to fight against their more aggressive nature.

Or something like that.

I fail to see what that has to do with sorcery. I’m not even sure what you mean by a stepping-stone between mer and man. Google suggests Elder Scrolls elves. From my limited ES knowledge, I’d think what you want is just humans of a different flavor and culture.

The idea is that this human like race would be ancient and cut off from the “modern” (BWG Human) race. Their ways would be different, their intuitive grasp of the mystic arts would affect all that they do. Their version of magic would just flow from them. The elder race could never learn to use “modern sorcery” just as the “modern man” could never learn “elder sorcery”

Originally I was considering using Art Magic to represent the elder sorcery as it seems like a nice fit. I have also started to play around with the idea of a seperate race which may be closer to what the storyline envisions (but a whole lot of extra work into uncharted territories for me).

I suppose the “mer and man” was something I picked-up from playing Elder Scrolls games, what I meant by that was this elder race would seem to be like an evolutionary stepping stone from elven to human race while not being exactly like either one.

Of course, I like the idea but I may well be too close to it to reconize its downfalls (which is why I seek the wisdom of the forum.)
Help and guidance are, as always, appreciated!