The GRD ability to use AAA batteries is an often overlooked feature either by camera reviewers and users. Of course, the AAA batteries are not very powerful and cannot replace main battery. But it's definitely nice option in cases all your GRD batteries are out of power. I'm just playing with GRDII and AAA batteries and here are some experiences. I'm now testing pair of rechargeable NiMH batteries - 700MAH.
My first experience with AAA batteries was not very good, because I found the AAA battery compartment too short or the contact springs too strong for a given batteries. Or maybe the batteries are too long? Simply, when I put the batteries inside the camera, I was hardly able to close the battery door and even if closed, the door seemed to be somewhat bend and not closed tightly! So I immediately removed both batteries and tried to cut the plastic cover on both battery sides. It does not have any impact on the battery function and I'm now able to close the battery door without using the force. But it's still very tight! I think the contact springs are really too strong.
Now about the camera performance on AAA batteries. The sad truth is that the focus and LCD refresh rate is much slower. It's probably because of significantly less power obtained from AAA batteries comparing them with main battery. It's like if you run laptop on batteries. The laptop is visibly slower when run on batteries.
I cannot inform you (not yet) about the number of shots taken with AAA. But I'm sure it won't be anything close to main battery