I have had nothing but good luck with my Lumatek 600w dimmable helps when you can set your light at different output levels when the plants are young.Hitman40
I heard once they become around 2 years old with everyday use that they will start to have problems.. They are fully warranted for those 2 years as besides the fact that they literally pay for themselves in two years..
i'm using a 400w dimmable lumatek, only going on 7 weeks though. I have used the whole dimmable range. So far flawless. I only wish I would of bought the 600w.