gtrestoration, a Radium 250wattSE is made for a M80/HQI ballast actually... not being overdriven one bit. I hear you on the output, but I need more... your tank is about 6" narrower, and 6" shorter (48x30x21"h). FWIW, the Ushio 14,000K is about 20% more output than the Radium, or the G-man which is another 20% more over that: both nive fits. I also prefer a 'full spectrum' with lots of blue. 20,000K and bluer 14,000K halides alone leave out the warmer spectrums all together and look monotone to me. The coloration that horkn talks of with this daylight halide and blue+ T5s is no joke. I have yet to see any halide only or even T5 only lit tank compete growth and color wise. The T5s also fill in where the pendant isnt hitting along its movement... preventing the darker areas from dropping down in PAR too much and keeping the whole tank in 'daylight' levels, even when the halide is at the other end. Julian Sprung thought this sounded crafty and very effective. With a single halide, you would have darker shadows left in the tank.
want2reef, actually, I would get worse coverage front to back with the reflector mounted perpendicular to the front. Its a common misconception, but the wider coverage/higher output on these reflectors is across the short width of the reflector. The bulbs put out less light in the direction of their sockets. So I do have the reflector positioned for the best coverage front-to-back already. As far as moving closer to the ends of the tank, I had started like that... with the light moving about 30"... but its overkill. The travel distance is only 2' now, and plenty of coverage.
salmon alley, as far as the Agramover, I cant comment. They are most likely similar, but I know that the Gualala is approved for use in humid environments w/o rusting, with sealed control electronics and wiring. The agra looks more 'DIY' which means exposed wiring and rust is more likely. Perpetual98 has one I believe... you could ask him. I also wanted the most compact unit so I could mount it inside my canopy with minimal clearance problems... the agra is a larger unit from what I have seen.
As for the tank, it is 30" front to back, but due to the 3" euro-bracing, the opening at the top is 42"x24". So I can have the T5s spaced out more (I was going to have 6-8 T5 bulbs in the original plan so I could play with bulbs and timing more) and simply angle the reflectors inward.
So yes, I would have two 2.5" reflectors in front of and behind the halide inside custom housings. The stealth reflector is something I am considering as well... it is slightly smaller, at 11x11. This could be useful. I would imagine it to be slightly less spread/penetration than the 14" version, but still... loads ahead of the PFO. I have the lumenarc DE pendant already though... so we will see... everything is a comprimise though.