GX100 arrived! I'm now at work, so I cannot start with thorough comparison right now
But I promise to post some test shots and thoughts about GX100/GRDII during this week. At least few initial comments:
Better handling because of slightly larger grip and smaller LCD (which means better buttons layout for single handed use). However, for FN button is required second hand. So at this point, the GRD/GRDII is easier to control with one finger.
GX100 is noisier (in terms of sound). It's not that noisy as GRD, but it's definitely noisier than GRDII. So if you are looking for a silent camera, get the GRDII.
GX100 RAW writing is a bit slower than GRDII but still miles ahead of GRD RAW speed:
1GB Transcend 80x (4:3 RAW + Fine) ................................ 11-12/6.1-6.4 (n. of blinks/secs)
1GB Transcend 80x (4:3 RAW + Fine) ..................................... 8/4.5-5 (n. of blinks/secs)
GX100 LCD is as good as GRDII LCD (though it's smaller - GX100 2.5/GRDII 2.7")
Menu font and graphics is the same as in GRD. GRDII font and graphics is noticeable smaller so it covers smaller part of LCD.
GX100 mode dial is not locked and the mode symbols are printed (GRD has the mode symbols engraved).
The body is plain without the small dots (which makes the GRD/GRDII body less slippery and more attractive).
GX100 really allows to select all shutter speeds for all available apertures (in M mode). I would really like to know why it's no longer possible with GRDII???
The GX100 lens is wobbly (front lens element), but nothing tragic. I would expect much higher wobbling after reading all these reports about how bad it is? In addition, the lens is centered. There is the same amount of tolerance if you move the lens up, down left or right and it always returns back to the center position. So if you do not intentionally move and hold the lens in off-centered position, the wobbling should not have any impact on the image quality. The "wobbling" happens only if you push the lens manually. Not if you move the camera up/down.
The EVF viewfinder is nice! It's much better than any other EVF I ever saw. It's clear, detailed, no delays even in dim lighted rooms. The only problem is visible if you point the camera directly to a light source, so you can expect the same light streaks as you can see on the LCD. The downside of this optional EVF is its size. With attached EVF is the camera no longer pocketable (without risk of ripping your pockets).