Hey Darren,
I have a 48x22x17 reef tank and I am running dual 250W HQI with the Galaxy ballast and the Lumenmax Elite Pendants. I am using the Phoenix 14K bulbs as well. I have the pendants suspended about 14" above the tank, thats the top of the pendant.
I am finding this to bee too much punch as my zoanthids and some LPS have bleached a little, but if I put them at the bottom they are okay. I am going to swap my Lumenmax pendants for the new Hamilton Cayman sun which should spread my light out a little more. Right now my pendants are 10" deep so it really concentrates the light.
I think on a 120 a MH would work great you just have to be careful what your using. Go with a shallower fixture and be able to adjust the pendant height if you need to.
I used to be a big fan of T5HO but after going to MH I havent looked back. I plan on adding and LED supplement this winter to add to the amazing color "pop" the Phoenix bulbs already have.