Variable Wattage Digital Ballasts???

I found a site selling variable wattage digital ballasts for $134

http://www.marinedepot.com/ps_viewitem.aspx?idproduct=LK1121&child=LK1121&utm_source=mdcsegooglebase2&utm_medium=cse&utm_campaign=mdcsegooglebase2&utm_content=LK1121

Has anyone used them before? The reason I want to get it is b/c you can switch from 150w all the way to 250w. Great for me since its a stealth grow. 150w for first month and a half of flowering and bump it up to 175w then 250 to save some money and put on a little extra yield
And when i get a new apartment i can put 150w mh for veg then switch it out for 250w hps for flowering..
???

I just bought a 400W Lumatek digital ballast, and it's adjustable. I was thinking of doing the same thing you're talking about when I start my next grow here soon. It hasn't gotten here yet, but I've heard great things about the newer digi ballasts. Much of the problems they had when they first became popular such as RF and cable interference, unreliability, and noise were acknowledged by most manufacturers and supposedly resolved with the newest lines. I'm gonna go about 75% for vegging, and then to the "super-lumens" setting for flowering, all with a 400W Hortilux bulb and a P.L. deep reflector. I'm getting good vibes from that setup.