A few random observations:
If you switch from AF to MF, the GRD3 remembers your focus point and shows the corresponding distance on the scale. I am not sure yet but this may be the best way of setting the manual focus distance for snap shooting. Best thing is that if you assign the AF/MF toggle to the FN1 key, then it takes only a single press of the button to switch from AF to MF or back.
I acquired a used GV-1 for about half the price of a new one. Haven't used it enough to form an opinion, but so far experience is that it is easy to use. The center AF point is not marked so if you are using AF, you have to sort of guess where the center is.
The shutter lag of the camera is minimum - unless you are shooting macro. The macro focusing seems to take a bit longer. I find that in normal shooting, the lag is almost absent. I have not had to wait at all, and the picture is taken instantaneously. Of course, in most cases, as you frame the picture, the camera has a chance to acquire focus, and then you can take a picture as you soon as you depress the shutter button.
At first I was puzzled by the default 5 minutes timeout for the camera to automatically switch off. I had assumed that it should switch off sooner to conserve battery. But while using it in a real situation I found that it was more convenient to just leave the camera on, so that it was always ready to take the next shot.
When using the optical finder, I wanted to have the lcd switched off. I may be wrong about this, but I found that if you switch the camera off and switch it back on, it forgets about the lcd setting so that you need to turn it off every time you switch the camera on.
Update: As pointed out by Chaka (see comments), custom settings do allow you to have the LCD turned off. It seems this cannot be done with the normal menu. I suppose that this makes sense in a way as turning off the lcd is a relatively big decision and you don't want it to happen by accident.