I think the popularity is largely down to the price point, I don't see *too many* other attractions than that.
I've spent quite a bit of time with a number of Shuker basses, and I've been very impressed with: Dude's Doodle (who couldn't be?), Dr.Dave's fretted 4 and Yorks5stringer's fretted 5.
I've got to be honest, other than those 3 basses I've really not liked any of the Shuker's I've played, that said:
[quote name='Roger Sadowsky']That doesn't mean they are for everyone---instrument choice is very subjective. What is nice is that all of us....Sadowsky, Lakland, Mike Tobias, Spector, Fodera, etc....all have lots of players that think we make the best instrument in the world! It's kind of perfect that way---don't you think?[/quote]