it's not. and i'm remembering that i went through this before many years ago. well, it is in theory, if i tuned the b up to an open c, but then i'd need jimi hendrix or michael jordan sized hands, and, as it is, i've met tween girls with bigger hands than mine. they're really freakishly small, it's sort of almost unbelievable, even. if lamarck was right, but alas...
so, i can't close this. but it could be years before i get that 21 fret guitar.
hey, listen - i can do sneaky, acrobatic things that hendrix' hands would get jumbled up in. it forces a specific style, but i can count as many times that it's been a benefit as i can that it's been a drawback. guitars aren't like pianos like that, there's too many angles going on.
the specific problem is that it's written in the third fret position, and there's consequently a lot of bass notes around there that need the hand to stay put - so they can ring. it's *already* kind of tricky, with pinkies stretching out to the 6th fret. if i tune the high e up to f#, i have to move essentially the whole melody up a string, because i need chords to ring through the high e and also to ring through hammer ons (meaning another solution would be to have six fingers). but, because the low g and f# are both prominent, that puts me in a situation where i need to fret from the 3rd (low e) to 10th (b) frets - which is not impossible in theory, it would just require hands much bigger than mine. it doesn't help to tune the a down to g or f#, because i have the same problem with the f# on the bottom string or the g on either of the two top strings - nor the e up, because it needs to ring quite a bit. a seventh string on either side would be another answer, but it's still not useful to me right now....