About the Beta questions...
SM57 - Sounds like an SM57
Beta57 - Moore crispy, tighter bottom. Kinda different in the top.
Beta57A - Even a little moore bright then the old Beta57.
The tight bottom of the Beta range can sometimes sound better on a Recto, but a lot different from a usual 57. I get a Meshuggah vibe with the Beta mics, and they will really benefit from a brown pre like an API or Neve...
However, I noticed how loud I record my Recto will have a really huge impact on the sound. Too low, shut-in sound, much top, less mid. Louder levels gives moore open sound, less top and moore mids....
How loud do you guyes record your rectos?