That's interesting. When you say brighter, do you mean when you look at the light source/fixture it is brighter? Or is the usable light brighter, i.e. table tops and surrounding (8' out side to side) light being thrown from the lamp in comparison to T8 & T12's? You should grab yourself a light meter and do before and after measurements. it might surprise you, especially measuring 3 months after the initial light measurements from your change over. If you have a friend with a spectrometer, then you can make it even far more interesting to capture the color shift over a period of time.