The only information I can find on 400w bulbs indicates about 120 lpw. The 200w Vero on my site, while being the most efficient retail vero lamp I know of other than the 1.05amp Vero 29 on my site, is not equal to a 400w hps. Comparing raw lumens it would be about 235w of hps directly compared to the 400w bulb, but without a majority of light experiencing reflector loss.
What the exact comparison might be I can only estimate, maybe 260-270. At any rate the ppfd in a 2x4 would be about 540, a strong veg lamp or a low ppfd high phototropic efficiency flower lamp. 3 in a 4x4 would provide a little over 800 ppfd.
Not overly exciting but still similar in cost per par watt to the other cob options available.
The truth is, led is just getting to the point of 2x per watt over HPS and when it comes to the Gavita it will take at least 70% efficient emitters to approach 2xing it, and it will probably be a while before anything like that hits the market. Pretty much every ad you've seen over the last 5 years claiming 2x hps has been a lie. Mid 50s are a possible reality now and I will have more of that showing up in the next couple weeks.
Anyway, I think the T4-200 is a solid lamp but am thinking the future of Tasty Vero will be short. I will have 4 different models in the CXB line, most of which haven't shown up yet and I will prefer to work with that. They will all be making an appearance within the next couple weeks, with a couple different drive currents represented. I have a specific focus but could lean higher or lower depending on where the interest is.