an awful lot of people have a downer on the shadow pickup series, and to be honest... the early ones were abit 'light' in terms of the durability... so maybe this is fair.
i have the (newer) shadow nfx on my bass, and i think the reproduction is pretty nice for an acoustic instrument... and a lot nicer than some of the other piezo based pickups... which just make the bass sound like it made of tin..!!
i like it because my bass sounds like my bass... but just through an amp. the preamp is pretty useful too, and does tend to offer a good flat response, but the smallest turn of the one will make a big big difference.
if you get the chance to try one of these... do... you might just be surprised
if you want toyur acousticbass to sound like an electric 'driving' thing of an instrument... then don't bother.