There was an article or two in Coin World when this was first announced. The reason the mint is planning to produce these on a double thick 27mm planchet is so that the ultra high relief will strike up better without multiple hits in the coin presses. My understanding is that when the mint was developing the Original Saints, they attempted a trial piece using a double thick $10 gold planchet and had great success in keeping the ultra high relief that St Gaudens sculpted.
It's gonna be a beautiful coin. Can't wait to see the 1907 original eagle struck up. I love the AGE obverse, but the reverse is mediocre.