the way i understood it..

a 2x overdrive (2 ballasts on one bulb) equals 1.7 x brightness

Since digital ballasts are built for it they automatically run at less than rated capacity (~1.7/2).

You can go up to a 4x overdrive (4 ballasts on one bulb) but this will only net a 2.4x brightness level.. same deal on ballasts.. Bulbs will last over a year.. which is about as long as you probably normally keep floros on plants.. well.. its as long as I do.. haha.. my old floros replace lights in my house and fresh ones go in the grow room.. haha

The moral of my question is.. and I dont mean to call your input BS or anything.. but where did that info come from? (note: my source is listed above).

I'd hate to lose a good idea because somebody somewhere said.. something.. there are alot of people that post bad things about overdriving floros but the ones I have spoke to in the past had virtually no basis for their negativity and had never tried it.. the ones that did do it swear by it.. anyone out there overdrivin?