I run a Blackstar in my flowering space along w/ a cooled 400 watt HPS so I can give you a direct comparison. I grabbed the LED for the same reason, need more light but not more heat.
The BS doesnt produce much heat at all, your plants can get pretty close without getting burnt. I like them and am pretty happy, but to be honest in no way does it come close to the power of my 400 watt HPS. Id say it falls between a 150 and 400 HPS as far as light. Ive noticed that the plans that stay under the LED do get a little more trichome coverage and the buds are as dense as under a HPS. The BS does not have much of a footprint, I can only fit 2 plants in 3 gallon grow bags under the LED.
In any case, if heat is an issue the LED is a good but expensive alternative with heat issues. . In hindsight, I should have just grabbed a 1000 watt HPS and a kick ass fan. Lesson learned I guess.