I just got mine today! I have a couple comparison pictures between it and my 350. Biggest difference is it's skinnier and sits in the pocket deeper. Carrying my 350 was definitely noticeable, the 566 disappears. Seems like the blade will be easier to sharpen, but I've only had it for about an hour so I have barely used it.
Thank you for the comparison pictures between the 566 and the 350. I was undecided between the two, but after looking at the side by side pictures, I much prefer the dimensions of the 566.