Again who is the "many"? Back in the T8 days in the 2000s, yes arcadia rated them for 1 year, and repisun rated the lows for 6 months and the highs for 1 year. But since the T5HO's came out, both companies, across the board, have rated all bulbs guaranteed output for 1 year. I guess there could be "folk" that are squeezing 2 years out of the arcadias(im one of the folk, and i have a meter) but i have not seen any reports of "bad zoomeds". Again neither company has a bulb factory, both companies use the same factory in germany, both companies use 7 phosphors.