Birdhaus 46

Birdhaus 46: 8 ohms; dimensions 18" tall x 14" wide x 10" deep; weight 23 pounds; 94 dB; 300 watts; -1 dB at 82 Hz and -6 dB at 62 Hz (so its low B is kinda weak) in vented mode; one pluggable port (useful for dealing with a boomy room); 6 kHz top end extension.  Mild bumpage from about 100 Hz to about 300 Hz in vented mode. Uses the Faital 6FE100. Price: $500 + shipping.

The Birdhaus format has outstanding dispersion.  Your band mates will be able to hear you clearly, in some cases for the first time.  While the cab is louder out front than to the sides, the tone to the sides isn't missing anything.  When the bass communicates to everyone on the stage, the whole band plays better.  This is more critical for some music styles than others, but being able to hear the bassist can be as beneficial as being able to hear the drummer.

This ultrawide dispersion benefits the audience as well, especially if you are accompanying unamplified acoustic instruments, or amplifying an acoustic instrument, such as double bass. 

While the Birdhaus 46 won't win a sound-per-pound shootout, the shallow configuration keeps the weight close to your body when you carry it, much like a suitcase, so in practice it's easier to carry than the weight implies.    

For louder gigs, the Birdhaus 46 can be combined with another cab, bringing with it the benefits of stage-width dispersion.