The Sony pretty handily beats the Panasonic for image quality, both in the center and at the edges, at the three comparable focal lengths I tested. That shouldn't be surprising because the sensor on the Sony has 8x the surface area of the Panasonic. But since most of my travel and landscape photos with the LX5 have been at low ISO (rarely as much as ISO 400) where sensor size is not as critical, and since I have always thought the images coming from the LX5 were "good enough", I thought I would use the LX5 as a "good enough" benchmark. The Sony 16-50 beat my benchmark!
I like the Sony a lot. Especially with the pancake zoom it balances nicely and feels very comfortable in my hand. I can even operate it with one hand, just like I do with point-and-shoots. But, I'm not exactly sure how it will fit into my style of photography (which includes the Olympus OM-D as well as the LX5). I'm thinking I might take it when I would otherwise take the LX5; however, the Sony is about 60% heavier. The LX5 fits in the pocket of my jeans, while the Sony fits in a jacket pocket. Lots to think about.
My next experiment is to compare the 16-50 image quality against my Olympus 14-54II. The 14-54II is supposed to be a step above a standard kit zoom. It's also a bit faster, perhaps by one stop overall. I would expect it to sharper, too. But you never know. You can buy the 16-50 for $350. The 14-54II sells for about $600.
Back to comparing the NEX-6 and LX5. Here are a few final thoughts:
I love the focus peaking feature of the NEX-6. I have five old Nikon lens that work beautifully with the NEX-6. (You do need to buy an adapter, however... about $20 on eBay.) And, while using old manual focus lenses, I like the implementation of the manual focusing and magnification feature on the Sony better than the Olympus. Yes, I know that Sony has no in-body stabilization but all my Nikon lenses are of short focal lengths where I would use a shutter speed of 1/focal length anyway. I don't really need stabilization with them.
The histogram on the NEX-6 easily surpasses the LX5. I use the histogram all the time and appreciate the RGB color channel histograms that can be reviewed after each image is taken. A big plus with the NEX-6 (and one of the reasons I didn't jump for the 5N or 5R) is the EVF. Another reason for buying the "6" instead of the "5" is the addition of a built-in flash. It is not particularly powerful but I like the fact that it can be pulled back to bounce the flash off the ceiling.
The LX5 has some pretty advanced features, too. I am surprised that the ones I like and list below are not also in the Sony. The LX5 has an size-adjustable single focus point. It can be made much smaller than the fixed size on the Sony, which I find very helpful for closeups. And speaking of closeups, the macro at 24mm is a very helpful tool on the LX5. Other great features include setting a minimum shutter speed (in P-mode) and being able to use Auto ISO in manual exposure mode.
One final note is that at this writing the new NEX-6 plus 16-50mm lens retails for about $1,000. You can buy the two year old LX5 for $250 at Amazon. And the new LX7, which seems to be sharper than the LX5 and has a faster lens, is selling for $449.