Your comparing apples to oranges. Most of the bulbs are available are HO. VHO drives bulbs harder so they are going to have more light output. I guess it just depends on if you want to spend the extra buck to get a VHO ballast to get all the performance out of your bulbs. VHO bulbs are harder to find, but you can always use T-5s and overdrive them. It will shorten the life of the bulbs quite a bit. A company called URI makes alot of VHO bulbs for aqauriums. I am not aware of any VHO other than the ones you mentioned for horticulture. T-5 HO are perfectly fine. VHO is more powerful plain and simple. Still not on the same page as MH lighting. I guess it just has to do with what you are trying to acomplish in your application and ask if its worth it.