Info about the I-Beam can be found at www.lrbaggs.com.I had one fitted to my Santa Cruz 000 and played it through a PA at the Cambridge Folk Festival (Club Tent, Saturday night**). I wasn't impressed and neither were a couple of other players I know - the bass was far too boomy. Of course, could've been the sound man that night, but I tried it thru a few other amps and got the same results.
My 000 has a big bass and rings like a bell (Martin Simpson reckons it's one of the best he's heard) so I reckon that it was a mismatch between pickup and individual guitar. I later had a Highlander fitted and that is perfect on this particular guitar (but very expensive, of course).
I bet the I-Beam would sound great on a mahagony Taylor.
qf
(** PS If anyone out there has any pics from Cambridge let me know: I'm the fingerpicking singer with the white hair, on about 8.30pm, just after the folksong foursome from St. Neots FC).