Very enlightening thread! Most ideas have good basis.

I want to share an idea that seems to get the best from both worlds for a COPIS owner (at least).
Why not use standard (not compensated) O2 reg feeding the ISC way the inhale cl and at the same time the second compensated O2 reg (must for deeper dives) connected to exhale cl?
Please don't hesitate to shoot

if its a joke
I think that makes lots of sense for a copis diver. Stage some O2 for bailout and feed some into the O2 byopass for the deeper excurion of the dive using a non compensated 1st.