[digital-audiophile]

1.) Slim unit design and weight (not as big an ugly as Mh units)
2.) Multiple bulbs allow individual selection to fine tune your colour preference & par (as opposed to only ~4-5 realstic bulb selections/colours available with MH)
3.) Less energy consumption
4.) Less heat (even after 10 hours on I can put my hand on the unit vs. MH of which I still have a nasty scar on my arm from a fraction of a second contact with a fixture)
5.) Less bulb replcement cost (up to debate)
6.) Even light in all corners of the tank, no shadows or MH "spolight" effect


Just a few points that sold me.