My tank is 27" deep and I run a mixture of M/H & T5 and really like the combo. 5x 250w 14k, 2x 150w 20k & 12x 54w T5 bulb mix. It's the best of both worlds. Lot's of colour, growth and still get the MH shimmer.
Another point about the MH is: are they HQI or single end moguls because between the two of them there is little comparison IMO. HQI all the way!