I really don't see passive cooling as an advantage, to me that just means 'no fans'. And I haven't seen any evidence that Luxeon leds are any better than Bridgelux leds. Besides, I can't run any of my bridgelux led fixtures (5 of them over 3 tanks) at 100% power anyway. So how much better can they be? It's like everybody says Crees are the best. Well back when leds were expensive and everybody was trying to cut corners it was a big issue. But now leds are at least reasonably priced compared to MH and t5, and they are certainly bright enough that Cree leds aren't the only good choice.
Ron, I must strongly dissagree with you and point out that the bridglux Button style LEds can only tolerate a heatsink temp of around 125 Farenhight and thus must be fan cooled in almost all applications we use them in for reef keeping. that is due to all the material between the chip and the heatsink. Luxeons can run with heatsink temps over 200 degrees all day long. this is due to a better thermal bond with the heatsink. if you are only comparing the LED die, even then the luxeons will be more efficient and run cooler (luxeon puts out more light at lower voltage and less heat and that is clearly evident on the data sheet)
sorry, this is getting dangerously close to arguing the which LED is better point, they all have their uses and strong points for different applications. and you've been a part of many of those discussions so no need to revisit.
RB fixtures have the advantage of being able to hand soder new chips in to replace burn ones or tweak the color, this comes at the cost of requireing fans to keep them cool.
Passively cooled is only a very, very good thing in the long run, some day your fans will wear out and fail, far before your leds, 50,000 hour life span, and once the fan fails the Leds will cook and you will notice fan failure by your lights not working or getting rapidly dimmer each day.
I don't mean to suggest that one fixture is "better" than the other, that is up to the end user to determine based on what they want for their setup. both are good fixtures cappable of growing any coral you want.