VHO's work well. Typically not as good a growth as MH and the color can be better or worse depending of course on wattage and what MH bulb ballast combo you are comparing it to and what VHO bulbs you are using.
As was stated earlier I can't understand why anyone would choose VHO nowadays though. T5's offer basically the same thing with a more efficient use of power and many more bulb choices.
......and yes I've used all three
I do still use VHO's for atinic supplimentation to my MH's. If given the choice now I might even go with T5's for that after using the T5's for a while.
FWIW, Chris