Out of these two choices only, what do you prefer and why? I have a 6 string Ibanez that I absolutely love to death but I'm starting to think I may have bitten off more then I can chew.
I like the 6 because you can tune it so many ways EADGCF, BEADGC, EADGBE and you can create absolutely amzing stuff when recording. But 6 strings are pretty rare and I know tons of people with 5's and they seem to be satisfied. So which do you prefer?
When I first got away from the 'tyranny' of the 4 string,

I of course went to a five, which gave me 5 extra low notes, and a few new positions to work with - nothing major.
Shortly thereafter I got a 6, and it was a revelation! Suddenly, a whole new realm of possibilities opened up - soloing in a proper 'soloistic' register that wasn't cluttering up the band, melodies with chords, chordal slap stuff, greatly expanded range, and it shed a whole new light on playing the bass and it's role in music. Practicing was fun again, and my playing improved so much because of the unlimited scope of the instrument. A complete revolution!
The five rarely got played anymore, I soon got another 6, and now I either play 4, which I've done for 37 years, or the 6's. Five's seem like a half-finished thing to me now - awkward for muting because of the low B, and not 1/10th of the advantages of the 6. You're still stuck in your role as an accompanist. The 6 brings you into the range of the saxophone, the guitar, the flute; pianistic chordal voicings are playable, and you can really fill in a trio setting with added chords while maintaining your role as a bass player.
I know the traditionalists will say that it's 'wanky', and there is some cheesy, trashy stuff being played, but it is expanding the role of the instrument; it's still a new dimension to us, and people are rightly experimenting with just where the boundaries of taste and musical expression are. The 11- 12 string thing - not for me - tapping sound too wimpy, with limited timbres, dynamics, and expressionless sounds. But a great 6 that fits your hands, capable of a vast array of right and left hand techniques and dynamics like the MTD's - priceless, capable of a range of musical expression comparable to any great acoustic instrument, and musically unlimited and marvelous.
And for teaching it is also a wonderful thing, because I can play the heads for my students while they're working on a bass line in the proper register, where the melody isn't clashing with the bass. And I can teach them the 'heirarchy of the groove', with the bass line, a drum machine, and me playing chordal grooves so the student can hear the interaction of the parts and really define the role of the bass for them, even if they're on a 4 string. It has greatly improved my ability to teach, without having to resort to the keyboard, which is still essential, or course, but not always readily available and can confuse the issue for some students.
Anthony Jackson, the inventor of the 6, is definitely among the greatest musical minds our instrument has ever known, far beyond the realm of just a player, wonderful though he may be at that.
The 5 to me was kind of like adding a Hip-shot tuner to your bass - a few extra notes, kind of handy, but no big deal. The 6 is a whole new instrument, with a new world of greatly expanded musical dimensions.
Just my humble opinion; some of my favorite players still play 4's and 5's.
Merry *.*
Cameron