[Ninong]

Since the original question concerned HO T5's, here is a comparison of 4-ft HO T5's with standard output T12 fluorescent lamps that I found online.

Sunlight Supply
Tek-Light T5 High Output Fluorescent
Indoor Plant Grow Lights
These new high output fluorescent lamps have an extremely high lumen per watt rating compared to standard fluorescent bulbs, making them extremely suitable for growing and maintaining plants indoors. Each 54 watt, 48 inch long, high output fluorescent bulb produces 5000 lumens, or 92.59 lumens produced per watt of energy consumed. By comparison, a standard 40 watt, F40 cool white lamp produces a mere 1260 lumens, or 31.5 lumens per watt.

High output fluorescent lamps have a very low heat factor which allows the fixture to be hung extremely close to plant canopy, thus increasing usable light levels. The TEK-LIGHT(tm)'s exclusive 9-bend reflector is made of imported German 95% reflective aluminum to drive every available lumen of light to your plants. Light output is 300% higher in this high-tech reflector compared to cheap fluorescent fixtures.

Here.

P.S. -- Something I probably should have mentioned earlier but didn't is the fact that there is often little correlation between lumen and PAR output. This is because the narrow band response of the human eye is not the same as the response of zooxanthellae. It's true that we compare lamps, especially fluorescent lamps, in lumens but it would be much better if we could compare them based on their actual PAR output instead of their lumen output. Remember, lumens measure what we see, PAR measures what the zooxanthellae "see."

Another point to remember is that the ballasts make a difference, too, especially with metal halide lamps. With fluorescent lamps, electronic ballasts are pretty much standard now so you don't have to worry about comparing magnetic ballasts with electronic ballasts. With metal halides, there can be a huge difference between ballasts and magnetic ballasts often produce more PAR than electronic ballasts.