I am happy with my six string baritone, although you do have to be a little careful if you use the traditional set-up, with both the first and third courses in octaves, and a re-entrant fourth. The bass string in the first course can be overwhelming, like Kanaka196 said. If you do want to use two octaved pairs, if you tune up two or three semitones, the octaved first course is not as heavy.
I usually have mine in "linear" tuning with unison first course and the third course in octaves, and it adds not just a fuller sound, but a little range as well: the "high" note in the third course is a bit higher than the first course, and so you get a little more upper end.
As long as you are mostly strumming (as I am until I get better at fingerpicking), I like the six string a lot, and it does not require the same amount of force to make chords as an eight string. In a baritone size, especially with wound strings, it does sound more "guitarish," but that is fine with me-I like guitars.