Mark,

I had 400w of mh with vho sup. Went to 6x54w t5's. love it. i've heard wonderful things about those power modules. if your hood is enclosed you will more than likely need a chiller. I have one on my 75gal. My only concern was mentioned above, depth. My tank is only 18. Do you intend to house sps at depths greater than 20"? If so, might wanna consider option 2. I will say that my power bill went down 30 bucks when i changed to t5's. Everything else on the bill remained constent. If you do go t5's i would recommend getting ATI brand bulbs. Best bulbs on the market by far.

Goodluck!

Kurt