I just found these sites today; some builders in France and Sweden have begun work on their own version of the Hagstrom Bisonics. could be really interesting, but all the info I have found is leading me to a dead end of sorts, because I can't find sound clips or anyone who has used these to give a statement about how they sound.
www.urbanpickups.com/ (http://www.urbanpickups.com/)
www.daguetguitars.com/
http://www.talkbass.com/forum/f8/club-dark-star-731040/ (http://www.talkbass.com/forum/f8/club-dark-star-731040/)
(conversation gets interesting about halfway through this thread.)
Also on this topic, anyone tried pups made by David Schwab of SGD lutherie?
If you follow the link to Urban pickups, just click the Lyssningsexempel which takes you to sound clips on Spotify.
The last clip among the urban clips is classic Bisonic. It compares pretty closely to the clips on Fred Hammon's site too.
Thanks for looking at this. I don't have spotify, and I couldn't get the sound clips to work on my computer. The builder has stated that these are very expensive to produce, hopefully he'll have better luck at this than Fred did.