Just a point I haven't seen anyone else make that would seem to merit mentioning...
One could choose to have a 29 fret fingerboard, which (assuming BEADG) would yield the exact same range as a 24 fret 6-string (B0 to C5).
It strikes me as interesting that, in THIS community, with all the innovation and customization, extended fingerboards seem rare. I've actually never seen another Alembic bass or guitar other than my own which has more than the standard (due to Alembic, largely) of 24 frets.
But it is a legitimate option that players wishing to extend their range should consider... consider the pros and cons of. Really, I frankly don't see any con. Attempting to plays devil's advocate, some might object to the necessary consequence that the neck pickup must be displaced if one has more than 25 or 26 frets... but all I can say it the neck pickup on my custom 8-string Europa bass sounds awesome, and second to nothing. It has a fabulous powerful sound which contrasts the sound of the bridge pickup perfectly and normally.
When they built it, they asked me if I wanted a little extra cutaway to access the higher frets, but I wanted the normal cutway; this gives me really good access for the 25th and 26the fret, then each one gets harder to use, and less practical for anything fast/repetitious.
But I think with just a little extra cutway, a 29-fret 5-string would be a worthwhile option/alternative to a 4-string or 5-string player who is apprehensive about getting a 6-string due to size/complicatedness.
As far as that goes, my .02 cents worth would be to get a 6 string AND an extended fingerboard. My 6-string Elan is EASY to play... EASY!!! Personally, I consider a 6-string to be the minimally desirable amount of strings. There is no reason at all why a 6-string should be viewed as significantly harder to learn or play. And if you have small hands, just get a shorter scale with a smaller/thinner neck and fingerboard. Sure, if you get something bigger than you can handle, that may give you a bad experience, but I think most people should be able to handle a 6-string provided it is built for them. A medium long (33) or short (32) scale Balance K made with light woods would be easy as pie for most people to play!
I think nearly everyone should be able to play a 6-string and love it... if, of course they want to. And of course, it is certainly one's perogative to NOT want to... but WHY wouldn't one want to? How many guitar players would consider buying a 5 or 4-string guitar... probably not many.