Interesting one would that be mate yeah but tbh doing/comparing this with autoflowers makes no real sense with autoflowers, each seed can be different/different phenotype, only way to do this is with clones from photoperiods. Growing a single auto, comparing it to lets say a SOG with 36 auto's is just luck of the draw to which one is picked.
I feel ya mate, matter of perspective too. But if you have limited 'space' and want to grow some variation this method is prob not best for you.
If you really want to go all-in, I would say you estimate gr/watt / m2 (or sq. ft for you USA folk) / Time spent (weeks from start to harvest).
This is the only variable that makes sense to compare it all.