My goal with EOM's revision was to make it so that it's not too hard to slide a few numbers around and change the flavor of the magic. Sure, using EOM or any other new magic system will take a bit of time to get used to, but it's not much worse than learning how to run a D&D combat or a Spycraft car chase for the first time.
With EOM, though, if you want a Cthulhu-esque magic system, we have rules included in the core system that says how you go about casting a spell if it's too high-level for you. (And we're going to include more detailed rules to emulate the sanity stuff in the expansion, Lyceian Arcana.) If you want a psionics-esque system, you can say, "Okay, these elements aren't available, and you can't use the Summon spells," or something like that. The main EOM book is intended to be very broad, and we're going to give advice on how to twist it to your particular setting in Lyceian Arcana. That's what I think our best selling point is; you can easily use Elements of Magic for whatever type of game you want, while most other systems are designed specifically for pre-made setting.
If you're going to mess around with alternate magic systems, I suggest you settle on one or two systems before you get into a long-term campaign. I got very used to using the old PsiHB and Mindscapes together, and I made a lot of changes to my setting so that its feel made sense with those two together. I probably wouldn't use Green Ronin's rules if I got them right now, because I'm already set in a particular groove.
Doesn't mean I wouldn't want to see them. I could always use them later.