Update:
Yesterday I took the 5/04 developer build and stripped out the bloat (which was minimal, pulseaudio, network-manager, alsa, avahi, blah) and added the stretch sources, while keeping the linaro sources. updated; upgraded; purged; upgraded; purged; solved dependency issues; rebooted - in a cycle for about 20 minutes and ended up with a nice stable stretch build with both wifi & bluetooth running nicely, other than that pesky 272 bug. I even updated with the most recent boot-loader again for good measure.
Then I added LXDE, alsa, pulseaudio, etc.
With NetworkManager stopped all is stable and I was able to install a bunch of audio / visual packages and start broadcasting both audio wireless throughout the house (working on video).
Of course I am not using anything other than USB wireless keyboard mouse, bluetooth speaker, pulseaudio-dlna, HDMI, so I am not exactly sure what I broke from the standard build by quasi-upgrading to stretch.
I noticed that the wifi starts to degrade (ping times go from ~1ms to sporadic ~30ms to 50ms) once the CPUs are pegged at 50%+ and RAM is pegged at ~90%, which I guess would be expected. I’m sure there is some tuning that could be done, which is admittedly beyond my capabilities. 272 remains the biggest issue.