As for power consumption, Its not looking good, but it's still looking better than a GameCube. Unfortunately my original estimate of "about twice as much power" is accurate.
For frame of reference, the 4 layer boards use ~5.5 watts for GameCube games and about 6 watts for wii games. If the wii uses 20% more power during gameplay than the wii menu, it will put us right at 2x.
Even worse news for the optimists. This board uses a Broadway B, which although is on the larger substrate, is supposedly a 65nm chip. The Hollywood is a Hollywood AA, which is a 90nm chip. Both of these chips are the final (and probably the most efficient) iterations before shrinking the substrate. Initial tests showed the RVL-30 showed little to no efficiency improvements.
Tl;Dr: The tested conditions are likely the best case scenario for a 6 layer board.