Good decision. If he is fit enough, why wouldn't he?
At least one title is a lock, so despite 250 Auckland points dropping, he will keep his ranking nice and secure with (at least) 2 ATP 250 wins in the non-countable section.
This will also be a good opportunity to gain some confidence against Nadal for AO, just in case.
If we look at the rankings:
Nadal is ahead by 290 points.
Fourth seed for AO unlikely (if even possible), but here is what they are defending up to RG:
Nadal: 1200 + 360 + 360 + 1000 + 500 + 90 + 1000 = 4510.
Ferrer: (250*) + 360 + (250*) + 500 + 45 + 180 + (10*) + 300 + 180 + 360 = 1925 (2435*)
*Note that some of Ferrer's points are non-countable.
I know this is a little far away, but since there is such a small gap between them and such a big difference in the points they have to defend, Ferrer is for me the favorite to have the #4 seed for RG.
Of course he could get stuck with Federer/Nadal which would suck, but if he is lucky enough to end up with Murray and Djokovic in his half, it could make a huge difference.
My apologies for getting a little off topic, though. Best of luck, David. I sure hope I can watch it all closely