In support of what Emilya said RE: LEDs. Check the reputation of any company you buy from. Make sure they have a local (country) representative and that there are no issues with their service. I had 2 Welthink lights fail after 18 months of use. Both were replaced within 2 days of receiving my shipment with no questions ask. I can't see that happening with many of the "UFO" brands available on e-bay...

H2G, I think you are making the point that many smaller colas will out produce one main cola? I have two side colas now that are as big as any main cola I've grown. That is the point of SCRoGing. Many somewhat smaller colas = more than one main cola.