. 1000 watt hps @ 2ft is 35,000 lumens = 4375 lumens per sqft.
A 1000 watt bulb can produce as much as 135,000 lumens, not 35,000. In a 8sq. ft space that would put you at almost 17,000 lumens per sqft. Much more than the t5's, and probably much more than your plants could use if you built a proper tent with bright diffusive walls. A 400 w HPS or a 4' 8 bulb t5 setup would produce enough light for that space, although the t5 will use more watts and produce less lumens.
t5's are not more efficient in producing light. HPS is the most efficient way of producing light, followed by MH, then high efficiency fluorescents. Look at the lumens per watt of a high quality bulb and you will see for yourself. A nice 400w hps will produce almost 60,000 lumens while a 4' 8 bulb t5 setup will use over 400w and produce under 40,000 lumens.
fluorescent bulbs do produce much less heat than MH and HPS. This is because they don't have a filament burning at several thousand degrees.
As for penetration, the light from a point source diminishes at 1/r^2. From a theoretical infinite line source light diminishes at 1/r. For a typical rectangular hood, the light will diminish somewhere between these two rates. The more surface area your hood has, the closer it will be to 1/r, which means more penetration. This is in addition to the effect of leaves being able to block light from a smaller source. So whether you use a bunch of fluorescents, or H.I.D.'s with hoods, your penetration will be based on surface area of the hoods and the total lumens produced. T5 hoods spread the light much more evenly than most HID hoods, mainly because of the size difference of the bulbs. On the other hand, as noted earlier, you can produce much more lumens with HID systems and I believe the raptor hood provides very even diffusion with a large surface area and dimensions that fit my room well.
