I use an 8 bulb tekkie with all ATI bulbs... bulb quality definitely helps... i cant comment on the quality of the OPs product link, but I dont think they have the reputation taht the teklight has... and of course, the ATI fixtures are awesome, but twice the price of even the tekkies... but as for the original question of 8 bulbs versus 6 bulbs? i will say 8 everytime... but thats jus me... again, i use and 8 bulb, and kinda wish it was 10... overkill or not... it prevents me from having to add lighting when i upgrade to a wider tank or a tank that is up to a foot longer... anyways, i say 8... but the quality of the fizture has ALOT to do with it... GL with whatever you choose!