well like most of you I've used simple transducer pickups...but unlike most of you, I use them near exclusively lol. I've never had a feedback "problem"...I've played them through amps and pa's, but I dont play with alot of people or electronics, so maybe thats the difference.
I also know Ted Crocker personally...he's a genuinely likeable, veneer loving, beer drinking, old school hippy. That guy is extremely talented, you should look at some of his guitars, homemade pickups, harmonica mics, stomp boxes etc...awesome stuff. He doesnt do alot of business off etsy...he just keeps it around for a little extra exposure. You can see more of his stuff at
http://tedcrocker.com/
He makes these for cigar box instruments and does sandwich them for feedback control, but also to protect the element, dull down noise coming from the body, clean up the look and ease the installation by using his adhesive. He could wire you a preamp if you'd like as well...the guy can do it all.
Ted has a bad foot (good lord, I wont link the pics), so he makes his living doing this stuff...consequently, all of his stuff is well made.