Do Baritone Strings always sound a bit dull/dark?

Always always use a tension calculator and buy individual strings. I have a free on I can upload that someone on sevenstring.org made ages ago. It calculates up to seven strings in a bunch of different scale lengths.
 
It all comes down to preference. 11-13lbs is the general area for the high E and 16-20lbs on the low E depending on your personal preference and how low you tune. Typically with Drop B which is so common in metal, your total tension should be somewhere in the 80-100lb area, and increases slightly as you go to lower tunings. I personally would never recommend going higher than 110+lbs, if you need more tension for lower tunings, you should look for a baritone scale guitar.
 
For a low B on a 25.5 scale guitar, yeah about 20 lbs. The calculator on sevenstring.org will give you total tension and individual tension for each string. Its a great tool.
 
I play a 26.5" scale 7 string in standard tuning but the Low B is tuned to A. I guess keep the tension at about 20lbs still tho ay
 
Great advice from The Winter Snow.

Since the talk about tension and all, I decided to put the string set that I recommended into a calculator for Bb standard tuning in a 25.5" guitar, which is what I use.

http://dl.dropbox.com/u/8838613/String Tension.png

Keep all variables constant and drop the low string a whole step to G# (the thread question) and you lose 4 pounds of tension in the bottom string alone.

http://dl.dropbox.com/u/8838613/String Tension 2.png

And this is WITH the heavier string set mind you, the one that I was advised was complete overkill and unusable for anyone besides myself. I can't even imagine the tension on the low string back when you used a 58 guage string, if even a 68 guage string is still technically "under" spec.

This is what I meant about fret buzz and high end harmonics, using the right string for the job just results in more of a pure bell tone rather than a slew of messy unwanted harmonics from a string which is not pulled to its intended tension.
 
That's the same system but I've got an actual little program that works it out.

I'm running 11-74 in drop G and the tension is very stable and similar across the board.

D 11 16.81 lb tension
A 15
F 19
C 28
G 38
D 52
G 74 17.26 lb tension

Works out great.
 
16 lbs on the thinner e string is too much for me, have you tried doing 1 and a half step bends on that sorta tension???
 
Ah good it works for you, mayb not for others tho, wateva floats your boat :)

I totally get that it's over the top, but it works really well for tuning stability, especially live. 17b of tension across the board just feels right to me. :D