Topic: why the size difference?

[jmz93]

Why are miniature omni's so much smaller than mini cardiods?

I went from tiny CSB's to larger AT853's, and while I love the directionality and sound of the AT's, I really worry
about them in stealth situations.  The recently announced DPA mini-card looks much narrower, but still quite a bit longer than small omni's. 

So, why is this a factor in microphone design?

and, if I were to switch back to omnis, but better ones, (DPA or Beyerdynamic), am I going to get much stereo imaging if
I record with them facing forward, say, attached to shoulders, when played back through speakers?  I'm not interested in
headphone results, hrtf etc.

thanks,
Chris