Fixture count and spacing in a greenhouse to supplement sunlight depends entirely upon how much sunlight you can expect to contribute throughout the year. If you want to grow year round than the fixture count and layout would be dictated by the shortest daylight periods. As a very general rule of thumb you can look for a single IG 420 to cover a 6' x 6' area with a 42-48" lamp to canopy separation.
You will increase bud density with the Pontoon and can push a longer flowering photoperiod with the 730's coming on at lights out. Halogens are high wattage and tend to peak @ ~560nm where they then fall off fairly rapidly. They do emit into the red-deep red regions but for that matter so do the 420 phosphors. I think the real beauty of the Pontoons is the low wattage 660nm diodes coupled with the 6 watts of 730's at lights out.
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On another note, if imitation is the sincerest form of flattery IG has to be literally gushing right about now. 1.6B people over there and they can't cobble up any of their own designs. Jeez!
http://www.inda-gro.com/IG/sites/default/files/pdf/CKRA.pdf
