DY,
” the question remains whether there is a halachic way to distinguish, aside from the practical non acceptance of the chumra in certain cases.”
There are certainly cases were we are meikal or somach on Shitos regarding the aspect of blios when its not a Ben Yomo.
I would venture to say that even though I’m makpid not to drink any CS, as per all poskim arguing with Rav Moshe (in addition to Rav Moshe himself ruling that you should try to get CY, see Vol 5), I would be somach on the shitos Pri Chadash (Note, which is muttar according to everyone’s understanding) and R Moshe if needed, in regards to Keilim that are not a Ben Yomo, as it is two Rabonon’s…
I think Rav Moshe’s teshuva is speaking about a Ben Yomo …