600W Ballast

I am thinking about replacing on old 400W remoted magnetic higbay warehouse ballast with a 600W digital ballast from HTG supply (600 watt DIGITAL ELECTRONIC GROW LIGHT BALLAST by Digital Greenhouse w/ bulb, cable(s) and open hood) for $200. The price looks great.

Does anyone have any experience with this system? Are the more expensive ballasts from Lumatek or Galaxy any more reliable?

I got a 400W/600W switchable ballast from NEXTGEN. I can run a 400W MH bulb and then change to a 600W HPS just by flipping a switch. No need to change the ballast to switch bulbs. That way you can still use your MH bulbs that you have. I got mine at my local hydro store for $258 and it came with a bulb. It only weighs 4 lbs and is cool enough/quiet enough that I can mount it on the wall with the mount it came with.

Does anyone else have any experience with this?

http://cgi.ebay.com/Digital-600-watt-HPS-GROW-LIGHT-600w-ballast-sodium-w-/390142475734?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item5ad64dbdd6