If you could just have the absolute basic features than contribute to a high quality recording, what would they be?
Sufficient channel count, sufficient mic power, transparent/low-noise preamps, the functional equivalent of Zaxcom "never clip" to avoid the need to think about levels until afterward, record/stop transport control, visual confirmation of recording and confirmation of signal to each chanel, and sufficient battery power. That's about it.
The specifics will be different for different folks. For instance, sufficient channel count for me is 4 to 6 (5 to 8 prefered), and sufficient mic power is 5V PIP (no need for phantom or balanced).
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Beyond that, I dream of a distributed "node" recording system eliminating the need for wired connections, requiring only minimal wireless bandwidth for control, with the capability of each node to continue to free-run if/when the wireless signal drops out.
For open taping each node would act like pretty much like the simple single-channel XLR input "plug-on recorders" which attach directly to the microphone, providing local battery, phantom-powering, and storage, yet with the ability to maintain 48kHz sample-level sync via a combination of wireless sync and free-run clock accuracy, wireless transport control, and wireless status confirmation. Associate any number of nodes with the control app and end up with sample accurate clock-sync'd recordings on each of them.
Advanced miniature version would include a pair of built-in, high-quality, low-voltage miniature microphones in each node (Mid/Side with choice of Mid pattern, or omni + hyper for dial-a-pattern), and each node being approximately the size of the miniature DPA boundary mount. Think DPA d:vice with embedded microphones, battery, recorder, and wireless control.