I like the idea of the PowerDock at my desk, but I'm not sure it would make the most sense as far as battery longevity is concerned.
Either...
A) You unplug it from the wall so it doesn't charge your phone while docked. Daydream just runs all day and your short-term battery life is shortened (by how much, I don't know). Or,
B) You leave it plugged into the wall so you never run out of juice. But the power cycles constantly compromising long-term battery health.
For a phone with a non-removable battery, I'm likely to err on the side of option A.