..The Tetramic is Audix capsules; the Soundfield are MBHOs.
Just to clarify, I don't think its been confirmed what make of capsules the Tetramic uses. I speculated in a thread here last summer that I thought they might be Audix, based on specs and outside appearance, but others who know more about this class of mic capsules seemed to think otherwise. I'll defer to them. In any case no matter what make they are, comparisons of the capsules as implemented in the Tetramic vs the same capsules in 'standard' mics is not straight forward or clear as it would seem, simply because of the unique calibration files applied to each mic based on measurement comparisons that correct the capsules. That's not to say that better capsules doesn’t matter, they certainly do, only that what we've come to know from using various and comparing makes of mics doesn't clearly apply in this case.
..As far as running 4 mics, and not mixing them, just because you can't decide what to run that night, I'm a big fan of that. I'll run ADK-TLs cards and AKG483 hypers, and when I get home I decide which I liked best. If it's a good room, not too boomy, I'll probably like the TL's source. If it's boomy, I'd probably like the 483 source. That helps educate me on what do bring the next time, and so on.
I think this is the primary value for most people. It can be a great way to better understand what setup and rig works best where, and to sometimes be surprised when the other one works better. There is great value in comparison.
As far as I know, I'm sort of the odd man out around here for recording most everything in surround for the past 4 years or so. But my target audience is myself, and I really enjoy the added value that recording that way gives me, primarily for listening enjoyment but also for optimizing stereo mix downs.
The musicians around the mic thing is cool and I've done that for some bluegrass campfire jams, but never really with the musicians wrapped all the way around back, which might be a bit gimmicky anyway. It's really been more along the lines of the nature recording aspect that John mentions- up close with the musicians in a wider arc than what would be normal stereo across the front, but mostly lots of ambient cues around the room from the fire, people laughing, different conversations, sounds from off in the distance, the night bugs, etc. Really, that environmental thing is one of the primary things I value in all of my surround recordings, even when all the conscious interest is from the front. It’s the much more real sense I get of being in the actual place of the recording, the sound of the bass interacting 3-dimensionally in the room, the more open nature of the direct sounds from in front, the crowd reaction all around. Oddly, I even find distracting audience sounds less bothersome because they are coming from a different direction than the music in front, and can be more easily ignored by my brain, than if they are folded into the stereo recording and coming along with the music from in front. In that sense, all of my music recordings benefit from surround in the nature recording realism sense. Plus it's just really cool to 'hear the room' in a great acoustic recording made in a really nice sounding space, and hear everyone erup in applause all around.
The other thing I really like about recording this way is using three front channels for L/C/R which is a big benefit even if I were to throw the surround channel information away. It really solidifies everything across the front and lets me adjust the apparent depth and up front presence with level and EQ adjustments to the center channel. That’s also the biggest advantage when mixing to stereo. I do add a bit of surround info for the stereo mix in as well, but that contribution is minor.
Note that none of the above surround talk applies to my use of the Tetramic up to this point as I’ve only used that for stereo so far.