Can't speak against them per se....by all accounts they are a nice lighting system! Vivid Aquariums has been running as set side by side with Radium halides on their 800 gallon system, so you can look there for some comparisons. I know another place doing a similar experiment. So far so good at both sites!
I would point out that they are not a focused light source, so there will be a lot of light-spill on a narrow tank like a 150g (assuming yours is standard 72x18x30H) unless the light is sitting just a few inches off the water. There will actually still be a fair amount of spill with the light at that height - at 6" height you'll still have a 20-36"+ diameter of coverage from 120-140º LEDs. (They don't specify.) If yours will be inside a canopy this won't be so much of an issue. (I do see they have a lens system you can add $$ on, but they give no specs for it on their site and the system is already pricey.) Technically, something with lenses like the Aqua Illuminations Sol system would be better suited to your tank's dimensions.
As you already mentioned, they are a fairly large expense - even relative to comparably featured lights. (Especially if you compare with DIY.) But if the price is within budget, you have no interest in DIY and they really meet your needs for the tank (at the price-level, this is really worth fleshing out!) then I don't see a reason not to try them! Worth case scenario if you don't like them is to sell them....and so far they appear to hold their value pretty well.
-Matt
