I should also mention, if I didn't already...
They used to tell us a panel consisting of both 1w and 3w diodes wasn't good, and that they should all be 3w. Personally.. I think that's incorrect. Reason being.. a blue diode needs twice as much energy to equal a red diode's output.
Here's from the Cree XP-E datas...
For the 450nm Royal Blues it's a bit harder to calculate, as they're measured in photon energy.. or whatever, but the 470nm Blues are 30.6 lumen @ 350mA, and require 3.2v at that amperage. The 630nm reds on the other hand, give off 56.8 lumen @ 350mA, while only requiring 2.1v.
Blues: 3.2v * 350mA = 1.12w.
Reds: 2.1v * 350mA = 735mW (not even 1 watt).
That's a difference of 385mW more for the blues (@ 350mA), and they
still produce 26.2 lumen less than the reds. That's why Cree only makes 1w colours (1.5w actually), and 3w blues and whites.
They told us lumen mean nothing when it comes to LEDs and plants. But if you really think about it, an LED is a "monochromatic" diode.. at least the coloured ones are. So just using common sense.. if one 630nm red diode put out twice as much lumen as another 630nm red diode, then obviously the panel with more "630nm red lumen" will be better than the other panel. Same goes for the blues.. higher the lumen/mW of energy, the better the panel.
But that's "only" if whoever designed the damn thing actually took that into account.

If buddy lays out his pattern, thinking he has a great mixture/ratio of reds to blues.. but keeps the blues at the same wattage as the reds.. diode per diode.. guess what? His ratio is no longer what he thought it was. If he was targeting equal amounts of energy from the blue diodes as the red diodes when designing his mix.. it's not going to happen unless he either bumps up the number of blues to reds ratio, or leaves the reds at 1w, and the blues at 2w.. or there abouts. Nobody cranks them to a full 3w.. if they do, don't buy it.. it won't last the 5 years or whatever the diodes are rated for.
Personally I think some of these panels fail just because of that... way more red to blue than what's needed for healthy growth.