Ran the 706 again tonight, switched the card this time. No issues.
I noticed that the prior outing my CA-9100's battery had run low, perhaps that contributed to the issue?
edit: what I thought was a clean go around actually had the same issues as the first time, just not at the spots I checked last night.
I suspect fault lies with the deck's (in)ability to write to cards, as I sent the deck's line out to my phone to stream via mixlr with no clicks present. That said, it is still befuddling to me why when I record at home I don't have any problems but in a show setting I encounter this issue. I had the levels set in both circumstances to peak well under -6 dB and the waveform doesn't look like brickwalling is the culprit.
ah well, back to the DR60d for me as well for the time being. Shame as I like the form factor and 6 channels.