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
75gal 6x54w t5's on icecap slr's 3 blue +, 1 pro color, 1 ge 65k, 1 uvl spuer atintic, iwaki 40rlt return, mak 4 on closed loop to om super squirt, mak 3 on etss reef devil, jbj artica chiller, aquamedic calcium reactor, DIY Kalk reactor, DIY media reactor, currently running half phospahte/half carbon.
Live in Uvalde, Texas. On the fish hatchery!