Howdy angel, im no expert, but from what ive read and heard, the 600 is the way to go and a couple people here are tryin' out the new digital ballasts that save aven more energy. As fer as the 220 vs 110, pack,n'2puff really knows his stuff in that department. Ill get you the link for the digital 600.
The didgital ballasts have been around for a little while now but there was allways a question about reliability, now that this company, Lumatek is offering a 5 year warranty they are becoming more and more inviting, i know i want one!