Good points, on PC's with equal parts the Maxwell architecture design is certainly a lot more efficient.
The issue I see is that the NX will have many bottlenecks holding the GPU back and will limit the efficiency over PS4/X1 by quite a bit. Due to the nature of handheld devices the best RAM we can hope for is LPDDR4, which with a 64-bit BUS at 1600MHz tops out at 25.6 GB/s, meanwhile the PS4 tops out at 176.0 GB/s and the Xbox One at 68.2 GB/s (plus a small pool of eSRAM which has a total of 204 GB/s). They also have 8GB, the NX will likely have under this.
The CPU used in the Tegra is also weaker. Per core the A57 at reasonable clock speeds it beats the Jaguar cores, but the Tegra only has 4 of those vs. 8 in the PS4/Xbox One. It does also have 4 weaker highly power efficient cores (A53) as well, but these aren't used at the same time as the A57 cores used so they don't change power levels at all. Instead they take over for the big cores when the system isn't being taxed much. It's called the big.LITTLE set up and really helps with battery life (which is great).
Bets:
1. If the Wii U sells closer to 10 million LTD by 1/3/2015 I win. If it sells closer to 9.5 million LTD by 1/3/2015 OfficerRaichu15 wins (winner gets 2 weeks of avatar control)--Lost.