I'm looking at the website, not sure where the review is. Link it and I'll take a look. If he's mapping the par footprint that would be useful information. Honestly though, I've already decided I don't like that company and wouldn't purchase from them. There is good reason for this attitude after years of people asking about these various brand cheap lamps. If they can't even bother to provide such basic information like how much light their lamp produces, there are other things wrong with the lamp besides poor efficiency. It's not 450w it's 200w and some of that is fans and driver loss, so output is around 165-170w. Efficiency is likely less than HPS so you'd be lucky to be getting 60 par watts from it. You would need 6 to replace a 1000w SE and it would end up using more electricity to run and cost more to purchase, so what's the point?
If you want to go LED check out Horticulture Lighting Group, Timber, and there are a few other companies that members here can mention. If you would consider DIY
@CobKits can set you up. You will need a minimum of around 350-375 PAR watts from LED to properly light a 5x5. Anywhere between 375 and 500 would be good.