Here's an interesting note on baritone guitars.
Taylor guitars is coming out with a 35 anniversary 8 string baritone acoustic. However, it ain't your Daddy's 8 string. It is basically a 6 string, tuned and set up, for baritone tunings...except the 2nd and 3rd strings are double with octave strings. Standard baritone tuning on this would be: B E A D octave D F# octave F# B.
Personally, I'm really excited to get my mitts on one.

There are so many songs out there that out wrote in a specific chord progression, that if you change the key, it don't sound right, bass walks, hammer-ons, etc. As I get older, my voice deepens, and I can't sing the songs as they're originally wrote. I think this will help me in that aspect. There, of course, would be a little bit of a learning curve at first, but I'm willing to give it a go.
I can just imagine how "full and round" a song would be with this guitar added to the mix. Just playing with 1 other guitar and a bassist, you'd cover so much musical ground, it's HAVE to sound good.