That would probably not be so hard to play-the top is just a five-string fretless and the bottom a doubled four-string. If you think that's something, check out this doubleneck seven-string fretted/seven-string fretless owned by TalkBass moderator John Turner:
I LOVES it, I WANTS it....must have the pressssus!!! I think I'm ordering one tomorrow, but in blue. Seriously, that is one KILLER bass. The "Jimmy Page" in me has always secretely wanted a double neck bass (8 string w/octaves on top, std. 4 string on bottom)....now I know who to do to. By the way, those two basses in the background look strangely familiar.....
Ooo! Ooo! Gimme! Gimme! The bass! not the little girl or JT...I'm not some kind of freak... sorry JT!
Heh, sounds like this Killer Curbow that Greg made a couple of years ago: More pics here: http://www.curbow.com/store/gallerypages/double neck/index.htm This bass is the reason I have my 8 string fretless. Since he had the 8 string headstock w/ straight string pull designed so nicely, I said to myself, "Hmmmmm.....8 String fretless could be fun...." I've been searching for my intonation ever since.
And BTW me wants one of those, too! Especially the natural finish maple :: "If only it were available in 6-string, lefty and that bluish colour that is on the Benavente "custom models and options" page - and some cash to go with it..." :wakes up and cleans up the pool of :