From what i understand it. The only difference between the 57 and beta 57 is the cardiod and hyper-cardiod. They are very similiar in sound. The really only advantage to hyper-cardiod is on stage when you need to get the source louder without feedback. Thus if your not using it for stage stuff, you should do just as well for sound on a normal 57.
The part about the beta having better bass response when upclose than the 57 probably has to do with the proximity effect. This is a guess, but i bet that the hyper-cardiod has more proximity effect than cardiod. This can be an advantage for some things. So you are right, just a bit different color.
wx3 - sorry dood but i had to say something. just because its considered the industries standard doesnt make it an automatic mic to buy. The main reason why this mic is so popular is because of its price. There are better sounding dynamic mics out there. Of course the 57 does have that standard sound, but what about getting something different to make your sound different than other sounds? I bet it would sound just as good but it would be different.
Also, becarefull with the Large Diaphragm condensor mix technique with guitar cab. If your doing it to make the sound bigger, your going the wrong way. With a distance of 5 feet you are going to get alot of room reverberation which in my opinion makes things sound thinner, and more distant. This might not be the case in all rooms, but im guessing that your recording in a living room or bedroom where the acoustics are not good enough for a technique like this to work right.
Another thing why i dont recommend this technique to new users, is phasing. If you dont understand phasing and dont know how to listen for it, there is a good chance you will get it. When you get phasing, it will basically make the sound disappear. If your going to do this, i recommend getting the sound you want with the 57, then mix in the condensor to liking. AND put the condensor on a different track instead of sub grouping them together, that way if there is a problem, you can easily take the condensor out and have the original 57 the way you liked it without the condensor.
danny