This seems like a really uprepared test and the results will be controversial at the best... You don't already have 2 seperate tents? You don't already have clones to use for the test? Surely you won't be growing seperate strains and have them all in the same grow space?
I posted my gripes about it on the other thread, but I have to agree.
To the OP:
Don't worry hybrid I'm super chillaxed. Just seeing issues before you even start makes us all :shrug:. I want to see the best outcome here.
You are already talking about how you will do this or that adjustments to make it "fair".
This test is about comparing the same clones which should have been cut the day your HGL light got there. But since that didn't happen then they should be getting cut today as day one of this grow. Under the same grow conditions, including environment. (And I think even light intensity would be best to determine which light spectrum grows the best plants.)
With regards to light intensity, I totally understand not keeping that metric the same because that is one of the selling points that HLG focuses on as an advantage.
But at the very least you should run both lights EXACTLY by the manufacturers recommendation! That way the spectrum/light unit is the only major variable in the grow.
Frankly anything short of a low variable grow is going to be controversial and inconclusive.