You need to use steel strings with this pickup because it's a magnetic design.
I've read many comments who said that you sound like a giant fretless bass with this.
On the other hand, there is much less feedback.
If you want to sound natural and "acoustic", I'd advice to avoid this.
An Underwood, Realist or K&K Bass Max will do the trick, and they'll work with any string because they use a piezo sensor.
(I deliberately avoided to list the Fishman BP100 because I don't think it's a good PU...)
On the other hand, if you have more money, there's the Wilson, Schertler, Barbera, etc.
Get a look here:
http://www.doublebassguide.com/
Very good site with a comprehensive guide to pickups and other gear.