A different kind of radiant heat

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http://www.schwankgroup.com/en/prod-lum-eco.asp

I just installed 10 of these (ECO-8) in a new 11,000 sq ft sheetmetal fabrication shop, typical iron bar joists and corrugated metal roof with 2" foam above, all open in the shop area, 14' to the roofline.

Any opinions on them? Experiences? I've started a few and so far I'm pretty pleased with them. They present some issues I hadn't encountered before. They require #16 wire to carry the 24V, 4 piggy backed together require a 100 va transformer and they also require active ventilation across the ceiling at the roofline to remove moisture. Took some thinking to come up with a control strategy but I think we have it nailed down.

The big question is paint the concrete floors dark to absorb the heat and warm the concrete OR light to reflect the radiant back up to the people? Apparently this is a hotly debated subject and I thought I'd present it here to see what discussion there might be. Pre-existing floor, which means no insulation underneath.