Oops, never got a chance that night and it slipped my mind. I'll give it a listen tonight.
Marshall, you need to at least carefully balance the level of the center card verses the omnis. Here's what I do when mixing this to 2-channel stereo:
1) Bring up the Left/Right A-B spaced omnis only, panned hard left/right. Balance their levels to get an even playback image. EQ if necessary to get them sounding acceptable. Then mute those channels.
2) Listen to the center cardioid alone to make sure it doesn’t have obvious problems. EQ if necessary to get it sounding acceptable, except you needn't worry too much about a lack of bass response in the center cardioid. Mute that channel.
3) Unmute the L/R omnis. Unmute and slowly bring up the level of the center cardioid, panned center, until it fills the center of the playback image and provides more "presence and proximity" than the omnis have alone, producing a smooth and solid panorama all the way across from left through center to right. Experiment with various levels, sometimes "just barely enough" center to be audible is optimal, sometimes about the same level as the omnis is right, and sometimes a good bit more level than left/right is best. Choose whatever works best for the particular recording you are working on. Listen for a while each way before making a temporary decision and moving on.
4) Fine tune the EQ and level settings. You have a powerful added degree of freedom in EQing things in that you can compensate somewhat for the center verses the left/right response and play them off each other. This can be very useful or highly confusing. The omnis are going to have better bass response, the center card is probably going to have more direct mids and highs. You can tailor each with EQ to complement the other beyond what you would have done with either alone, adn that can work really well, but don't go too overboard.
Part of what makes this work well is the wide omni bass at the sides of the image, and more direct mids and highs at center. To keep from going crazy with options, EQ the L/R and the center separately first so they sound good alone as a starting point, except as mentioned previously you needn't worry too much about lack of bass response in the center card, and you also don't need to wory as much as you might have about getting enough clear mids in the omnis alone. Get a good working level balance between them, then play around with EQing the center and sides slightly differently to get the best imaging.
I often end up with something of a diffuse field EQ on the omnis which emphasizes the ambient room sound (some high treble boost, but not as much midrange boost as I would use if I didn’t have the center cardioid in there). I also often cut a good bit of the bottom end and contour the low mids from the center cardioid to keep things from getting muddy or confusing. When you try differnet EQ settings, go back and rebalance the levels again.
After playing around with this for a few recordings you’ll get a general idea of what typically works, but the specific settings will be different for each recording. I usually have a fourth channel which is a rear facing center cardioid and bring that up last to balance crowd reaction, depth, and ambience.
If you are mixing to 3 speakers (Left/Center/Right) instead of 2 channel left/right stereo, the process is the same, but you may arrive at slightly different settings. If you have a home theater setup, try that out, it’s really cool. It’s great even with three channels, but with four I split the rear facing cardioid channel to feed all the surround speakers equally and the overall effect when you get the levels and EQ right across all channels is like a the holodeck- you are there.