I have 4 myself (2 car garage), will be getting another 4 (shop) and have about 40 on projects currently. When replacing 8 year old 4' T5 2-tube fixtures/wrap around lenses with the Pixies the perceived light is brighter but not 50% brighter. The ceiling gets less cluttered and with an 8' ceiling replacing a 4" thick fixture with 1/2" makes a difference in ceiling height, as you generally feel the ceiling to be at the bottom of the light fixtures.
I like them a lot.