A friend is considering, on the advice of a local legendary fiddle repair guru, a RIML (www.riml.biz). It's a mic which is mounted via a clip in the "C" side cut of the fiddle, requiring no instrument modification. It looks like a good concept to me.

Schatten Design (www.schattendesign.com) is another option and though I've never used their fiddle pickups, I have installed them satisfactorily, and I personally use their "Dualie" guitar pickups in several guitars (though I'll use a condenser mic whenever possible).

I dislike bridge pickups, much favouring soundboard transducers when I can't use a mic. In many situations though, a pickup is the best option to counter lousy gear, lesser p.a., inexperienced soundpersons, crappy room acoustics and whathaveyou. There's no perfect fix, but usually an adequate one.

Peace, Mooh.