I don't like those tiny little reflector pod fixtures either, always better to have a more open design i think for ventilation. I had 2 x 400W Radiums over my 4x2x2 and it gave me heat issues in summer when i was living in a house without air conditioning. :fun5:
I wouldn't underestimate the power of those 4 x 80W T5 tubes either mate, i'm switching to Giesemann T5's soon because my LFS is stocking them now and getting hold of ATI tubes is a pain most times with stock levels in Aus always being a problem it seems. I'd rather give the money to the LFS guys anyway as with the expensive freight charges here it doesn't work out any more expensive than shopping online.
I run my Radiums on either 250W or 400W HPS ballasts Wrangy.