Its not the expense or the brand of the LED which will make it more or less effective. You need two things for an effective light - enough watts to penetrate the canopy and allow for photosynthesis and the right spectrum of light. For flowering, Deep red 660nm is essential and then most manufacturers throw in some 630nm to round off the red spectrum, from there it varies. Some use orange, some yellow and then blue (some where in the 450 - 460nm range) white, some include uv and infra red diodes for increased resin production. (The bands used varies between manufacturers).
Its this blend of light produced by the LED and the power of the diodes used (preferably between 3 and 5watts for better penetration) that produce a good grow light. Although you can use less energy when using the targeted light spectrum of LED, the adage 'Watts is Watts', still holds true. Or maybe 'Sufficient targeted watts are effective, productive Watts' is more appropriate. I'm not sure what it is or if its yet been calculated but there should be an ideal wattage per square foot for LED's and by that I don't mean the claims made by the manufacturers. As a starting point I don't think there would be much point using less than 300watts of LED lighting, any less and CFLs are probably on par and a lot less expensive. Using multiple panels also allows you to place plants in the overlap between the lights as well as give them point multiple points to grow towards which, will encourage bushier growth.
Plants literally absorb the available electromagnetic energy (from the specific spectrums they use) of the light for their processes, less available (useable) energy = less plant.
Its never as simple an equation as which light is better. Air exchange (Nitrogen 78%, argon, co2, oxygen levels), water quality, nutrients, substrate and atmospheric heat and humidity will affect the plants ability to undertake its processes, grow and bloom.
