Refurbished ver II w/ tiltable screen/opt evf is selling for the same price...
I used ver I for 2 years and I used it more on the wide side which is faster side of the zoom. I got a used (like new) ver III last week from KEH with their last minute 10% sale. I went back to RX100 after my trials with g7x and LX100... I did a test yesterday but I haven't downloaded yet but it felt like it is the same af as ver I which I was happy with (not like g7x which backfocused with the macro/close range). I will check low light af if there is a change but I doubt it.
Adv of ver I
-Faster 28-35mm range and longer 100mm reach.
-Size is a little smaller due to built in lcd screen
-Cheaper.
Adv of ver III
-24mm reach and pretty much f2.8 zoom after that (28-70mm)...
- Tiltable screen w/ selfie mode
- EVF which is amazing, easily I can hand hold it at 1/10 sec at 70mm f2.8
-Same 1/30sec min at wide end, but auto ISO in M mode to adjust that
-Auto ND filter (you need it to shoot widen open in day light esp f1.8-2)
Mine came w/ extra battery and Sony grip which I prefer over the third party grips, since Franiec grip fell down from the ver I Asi-Akahi leather skin...
Downside for me is the warranty esp after 1st one failed after 2 years and the evf in the ver III might have a high chance of failing considering the mechanical movements it requires. I think KEH has short term warranty on the used equipment. So overall it is worth it for the price difference, but then when you look at the overall cost of RX100, it is a better deal with same sensor/body set up.
You can download Capture 1 to edit Sony raw images free of charge and pro Sony version is only $30 more...
Hopefully some other manufacturer will use the same 1" sensor, but with 4K video becoming popular I think some will stay with 12MP threshold until the 8K comes with the 2020 Olympics per Panasonic interview