Thx, I didn't know that little step.
I realized afterwards that the eUP display filter on the booking page now shows the copay too which I never came across before, and which may be due to promo being dropped recently per Cow or that I am usually G. Makes it straightforward to compare $85 bump for Comfort, or the $150 copay for Flex fare upgrade for YVR-YYZ regardless of the cabin type. Turned out to be L btw.
In the future I will get to fixate over whether the extra Comfort $$ is worth it without a guarantee of eUp if outside my window, but right now I am sticking to fully refundable fares anyway.