...Of course the first thing I went and did was to ruin it by reading the excellent literature from Barefaced on their website. Thanks to Jim Carr for that. It opened my eyes to so much more about the speaker world. Knowledge about how speakers work is great, but remember, you don't listen with your eyes. If you liked the tone before reading something on the internet, then you should still like it after. Keep in mind that while things on websites may have truth behind them, they are also marketing intended to sell products.
Now I'm afraid that my 4x10 wont cut it in a live setting either. Of course it sounds monstrous when I'm sitting there directly in front of it, or in a small room, such as band practice, but what about the poor dispersion? How do I know that my sound isn't crapping out everywhere but directly in front of my cab? Yea, I can go out in the room and stand in different places and have the band play something and have someone pluck some notes on the bass... but that will hardly give me an idea of how I sound at FULL gig volume in EVERY venue with ME playing. There are a lot of factors at play here, room acoustics, number of people in the room, PA quality, sound man talent, etc... You can have the best rig in the world and still have a crappy tone out in the room.
Whats more is that, now that I've read all of this, it makes sense. I've seen so many bands play with bassists that just sound muddy and overly subby even though they have a quality looking rig behind them. I'm sure I've seen bass players with 4x10 and 8x10 cabs that had an excellent sound, but maybe I was just standing in the right part of the room? Keep in mind all the different sound sources going on in the room. The guitar sound coming from the amp is very directional. Low drum notes, more omnidirectional, higher drum notes - more unidirectional, Keys most likely coming from only the PA with the vocals, etc... Things are going to sound different all over the room.
So, what we have here is a lot of various factors all going on that make up your onstage sound. Your best sound is always going to come from keeping your stage volume as low as possible and letting the PA and a talented front of house engineer handle the mix. Unfortunately, that won't happen in every place you play. MO, your criteria for choosing a cabinet should always be tone! If there's a cab out there that rocks your world and it just happens to be a 410, then don't sweat it. After that, you need to determine what your other important factors are. If your'e like 90% out there playing, then your going to be spending most of the gig right in front of your cabinet, so dispersion isn't going to be that important to you. If you are going to be running all over stage, then dispersion is more important, but might you better be served by a cabinet on each side of the stage, or even in ear monitors?
The long and short of it is that yes, dispersion is important. How important it is depends on a lot of things and for a lot of players, things like tone, portability, cost are usually higher up on the list.