when talking about t-5 lighting

You are right that your setup will put out strong light. At 1.6 wpg with the Tek setup, you are probably borderline high light. If you keep the lights fairly close to the water, you will likely be high light. If you can make a setup which allows you to adjust your light distance from the water, I think you will be able to have either low or high light with your setup.

 

I use T5's 2x24 (TEK with individual reflectors) on a 29 gal CO2 injected tank. These put out higher PAR reading than PC lighting of the same wattage (new bulbs on both during readings at the same hight). -Disclaimer-these reading are particular to my tank and lighting setup. It does provide a better spread of lighting over the tank vs PC's. Weeds grow well trimming about every 2-3 weeks.

I can't see T5's being used on "low tech" unless they are well above the tank. T5's appear to be very efficient for their wattage.

I didn't see what type of tank you are doing, carbon enriched or not, high or low tech?

 

I have the Tek II's over my tank. 6x39 over a 125 gallon. I'm only running 4 bulbs now and still get PAR readings of 40-70 at the substrate level. This is with the bulbs 10 inches above the water surface.

I didn't have my PAR meter when I first set up this tank with my first fixture of 3x150 MH HQI but I subjectively feel the T5's have equal if not superior penetration and definitely have better coverage (ie lack of dark spots and shadows).

In summary I don't see T5HO being part of any low-light setup.