I use both VHO's and T5's on my 40DSB reef.T5's are the way to go IMO/IME.They are much more efficient(3' VHO 95w -vs- 3' T5w39w).I prefer to run all my flourscents(VHO,T5,NO)on the IceCap660 ballast.This ballast will aloow you to run any combination of slourescents at the same time(I use 2 t-5's,1-VHO,and 1-NO)
As for bulb choice/spectrums,t5's are bettter as well.They maker daylight bulbs(6.5k),the make white 10k bulbs,they make blue(450nm)actinics,as well as true(420nm)actinics.The prices of the T5 bulbs are alot cheaper than VHO's too.I pat $13 for a G.E. daylight(6.5k),$15 for a Coralvue10k,$15 for a CV blue(450nm)actinic,the most expensive of the bulbsa is the true actinic which is($2.As well as T5's being cheaper,they also will last 18-24months when ran on an IceCap ballast(VHO's will get 9-12 months on the IC).The IC660 ballast actually drives the 39w bulbs at 63w and the T5's really are at there best when ran off of that ballast.I do use t5's on my other tank ran off of a WorkHorse5 and they are no where near as bright.The most important thing though about either flourescent light setup is ventilation.Make sure you put at least 1-4" fan in your canopy with 2 being idea.
FYI,if you have a choice,go with the IceCap T5 reflectors rather than SunlightSupply's reflectors.SS uses cheap boldholders on there reflectors that rust quickly which can actually crack your bulb(its happened to me).You can prevent it though by isolating the bulbholder from the reflector with a rubber washer and use marine grade stainless steel bolt/nuts instead of the cheap ones they supply.