Yeah the shaded viewport is terrible for flickering. If you turn on clipping plane in the camera it sometimes works to stop/reduce this. Although I like the idea of this Corona method better, if you really went nuts on the de-noise I think the smoothness would almost look painterly :D
Almost any denoising looks painterly to me :- D I can't stand the effect.
It's tough choice:
Viewport gives me clean anti-aliasing, proper shapes and textures being visible, but with no (or incorrect) light and flickering. It also takes some time to even generate those views, I am baffled like why.
Quick-pass render shows final look in not final quality.
I wonder how my clients would react, but if Yetcrows became "violently happy" ,it's something worth trying :- )