Hey Swingfingers. I've been able to test both these pickups on the same bass (older German Plywood with Velvet Animas) thru the same amp (older model AI Contra) on a least a dozen recent gigs, everything from quiet jazz duos in small rooms to full-on jump blues gigs competing with a loud drummer and even louder (!?) electric pianist.
Both pickups offer clean natural tones, even response, and can accurately represent the true sound of my bass for both pizz and arco. With both pickups always installed on my bass I find that I can dial in a variety of great tones at any volume by altering the mix between pickups rather than tweaking the EQ.
To summarize as briefly as possible, I'd say that the Schertler sounds better at lower volumes and the Fishman is more friendly at higher volumes.
In fact, for a jazz or any sort of "acoustic" gig where volume isn't really an issue I'll use only the Schertler with its own preamp directly into the Contra. It sounds just like my bass unplugged...full bottom end without boom, nice articulation in the higher registers, all the upper harmonics are there, and quick and even response for arco. Can handle slap pretty well too. In a couple of gigs where another bassist came by to sit I was able to listen the the rig from across the room and the tone was just as good from 30 feet away, much to my delight. As with most any pickup, proper installation of the Stat-B is essential for good tone. You'll have to shape the cork end of the unit to make it fit snuggly into the bridge wing. I always keep a few extra homemade cork and balsa wood shims handy. You can install the Schertler in either wing of your bridge to find the sweet spot for your bass...on the German bass which has a big blooming low end I put the pickup in the 'G' side wing. On another bass which had less character in the low end I had it in the 'E' side.
When I need to move more air and a greater intrusion of electronics is unavoidable, I've found that the Schertler can be prone to a typical nasal-y midrange bump much like a traditional piezo pickup, and that its clarity in the higher registers can be too much. I'd say that the Fishman is the better pickup if most of your playing is in loud situatiuons. It too sounds very natural and even for pizz and arco and slap bass, though it lacks some of the upper end articulation and sensitivity of the Schertler. I'd characterize its sound as being "rounder" with more thump.
Being able to switch between the two pickups is most valuable anytime I'm on a big stage having to compete with a full band or hear myself through a huge PA system...sometimes the high end of the Schertler is overbearing so I just dial it out a bit...sometimes I need that high end to cut through a mix so I just dial it back in. Onstage with the jump blues band and need more old-school tone? Dial in more Fishman.
So, as you can tell I like both of these devices very much and I'm able to deal more comfortably with the very inexact science of URB amplification.
Feel free to contact me if you've got any more specific questions.
joe
jokeisle at earthlink dot net
www.waybacks.com