Note that different kinds of wizardly power cause different amounts of tech problem. Molly has always been subtler than Harry, and always had an easier time of things. Harry's "lots of energy" boom-style magic is probably about the most hex-prone there is!
IMHO any game that has Ars-Magica-like "Flaws" is rife with potential alternates to the tech/hex problem. Just a few from Ars Magica:
Addictive Magic: Once you start casting, it's SUCH a rush! And it's just soooooo hard to stop... All too often you cast yourself into unconsciousness!
Painful Magic: It hurts to cast. Sometimes it hurts a LOT. Avoiding Backlash? Yeah*NO*. Doesn't happen, not for you...
Aura of Distrust: Every time you cast, there's this vague... taint about you. People just don't LIKE you when you have recently done magic. Cops hassle you, chicks hate on you (unless you dig guys, then THEY hate on you; unless you're bi, in which case EVERYONE's hating on you), bullies pick on you, etc... Even friends you have known for years get annoyed and tell you to "clean up your act." The bigger the spell, the worse (and longer-lasting) the taint.
And here's an idea specific to DFRPG: Natural Summoner. There's something about your magic... it thins the Veil between the mortal world and the Nevernever. Big spells actually open a gate. You don't have to TRY to do it, it just happens; and no matter what you do, it ALWAYS happens. Even worse: there seems to be some sort of "call" or "lure." Something comes through, WAY more often than with other Gates.
Maybe invent some kind of weird bloodline that's the source of your magic, and is vulnerable to something modern. Like faeries with iron, but not THAT... Maybe some sort of "Nature Spirit" ancestry -- you can't stand the touch of anything synthetic. Everything has to be animal-product or plant-product. No nylon, rayon, polyester, latex, etc etc etc.