Hey man! It's weird how people still haven't replied to you because I'm sure someone here knows the answer.
What I would do is use both units if you still have them and got good enough space/ventilation. For what I've seen, the 3W diodes SHOULD be more efficient so technically you should have a great deal more brightness BUT penetration might not be just as good. Mars Hydro is a proven brand and I'm sure you'll be happy with the results.
As for yield, it is my belief that when you up your wattage it becomes harder to keep up grams per watt-wise unless you do SoG or something. Still, your yield should of course increase dramatically with double the wattage. Then again, I have zero practical experience with anything more than 30W so I might very well be wrong. :roflcry:
UV and IR diodes are hotly debated. I personally believe in the increase of trichomes when using UV-B, but you certainly don't need it to grow potent stuff. My Delahaze (the 17W plant) didn't have it and she still knocks my socks off. One of my friends even gave up smoking because it was too strong for him and he thought he was going to die. Yeah.
IR isn't very crucial either. The main advantage of IR is the Emerson effect which allows you to give photoperiod plants something like 16 hours of light during flowering stage instead of just 12.
I've understood that both cold and warm white LEDs are something you want to fill the gaps between the other spectrums you're using. They're supposed to be very beneficial.
All this stuff is just something I've read online and before you decide to take them with more than just a grain of salt I suggest you check them out yourself!
