If you are looking for a great digital ballast you just cant beat the Phantom 600 Watt Dimmable Digital Ballast. I use these myself after trying others. They are bullet proof. Forget Lumatec. These ballasts can be mounted on a wall, stood on end or laid flat. They also increase bulb life by dimming or brightening gradually instead of all at once.
You might wonder why anyone would buy a 600 watt digital ballast. Well for one thing they are more efficient than a 1000 watt ballast. They give off more lumens per watt than any other size ballast. They give off less heat so can be placed closer to your plants. For longer rectangular areas 2 600 watt lights will give better coverage and penetration than a single 1000 watt hood will.
I have been using these ballasts for 2 years now without a single problem so I would recommend the Phantom 600 Watt Dimmable Digital Ballast without question. This ballast is no longer being sold separately so now you have to buy it with a hood. Check out the different combos here.