Using OBS to record a video was actually very easy 
I fly on an ultra-wide screen, but only recorded the center portion of the screen.
Was interesting to watch the replay to focus on the input viewer. I did need some left stick during taxi. But the weird yaw/roll that I had in an earlier version of the S300 is clearly not there anymore in the current 1.0.5.
So my personal summary is that the S300 flies absolutely fine in its current incarnation. Thank you @belatu42 for providing your input and motivating me to revisit this helicopter!
