Better to do the test differently.
Bunch of peppers in 1 gallon pots, try 3 plants per light.
Try to use a 250 watt HPS (or a CMH) instead, perennial plants like tomatoes or peppers don't need as much light as a marijunana.
Since you can just flower them for years as opposed to only have a short time window where you have to maximize flowering.
Peppers have the advantage that they have an easier time being small than tomatoes, and they're a bit stronger than tomatoes too.
I have a feeling the 680w one may have fried it too.
How was the ventilation?
Also with tomatoes you do want to supplement UV, it's one of the reasons why greenhouse tomatoes so often taste like ass.
The glass filters the light, ultimately ending in no UV stress.