I think that when 1 watt LEDs are used really close together almost like a single point light source, they can be more beneficial than one might think. The nice thing about the higher wattage LEDs is that they can be spread out more. Or used in smaller quantities in engines.
For instance, instead of using 100 x 1w LEDs in a 10 inch circle LED engine, you could get by with 33 x 3w LEDs in the same 10 inch LED circle engine. The light output/penetration differences would be nil.
The nice thing about 3w, 5w, 10w LEDs is that you can use fewer of them overall in a tighter area(with appropriate cooling) thus increasing overall intensity and penetration. Don't believe the companies that say multi-chip LEDs are not as bright as single-chip LEDs, it's total fucking BULLSHIT! The differences are nil. The real benefits from using 5w etc is that there is less wiring that you have to do.
See, the people that are having awesome results using warm white or neutral white high power, 100w SPOTLIGHT LEDs are using 100 chip 100w LEDs. The individual LEDs on their lights have 100 x 1w chips under 1 lens. No one would argue that they are "less bright" than 10 x 10w LEDs that have been spread out in a larger area because it would be a lie. A 100 chip 100w LED spot light that uses 100 x 1w led chips under 1 lense is MUCH brighter and more penetrating than a light that has 10 x 10w LEDs that have been spread out across a larger area than the tiny single-point spot LED.
These single LED spotlights are very similar to using an LED light that utilizes 1w LEDs packed into a small area. Yeah, the UFOs aren't really considered a "small area" like a single LED spot, but you get my point.
When an LED light is advertised, for example, as 90w, but only consumes an actual power draw of, lets say, 70w, it's because they are running the LEDs at a lower current than what the LEDs are rated for. They may be using 30 x 3w LEDs capable at running at 700mA, calling the light a 90w light, but only running the LEDs at 500mA. This is actually a good thing because it is going to make the LEDs last much longer(as long as they are properly being cooled.) It's just not going to be putting out the full 90w of light energy as they advertise.
The only way to find this out is to either ask the company before buying, or testing the power draw of the light fixture. There also may be a way of adjusting the current if the drivers they are using are adjustable so that you could crank up the brightness. Highly unlikely. You could also replace their driver with your own, but it wouldn't be cost effective.
As long as you are keeping your LEDs below 90 C(not positive on the temp), they are going to last their full potential time.