I bought a DXG ~2 months ago and love it. The big screen is sooo nice!
I also have a K3 wifi/3g. The screen contrast is the same for the K3/DXG (great!)
For the light web browsing I do, the DXG browser is fine. In some respect, I prefer the DXG browser in basic mode since it brings up most webpages faster and displays them in more of a text-mode-look and lets you see more information on the screen. The K3 browser can look a bit busy, esp. on a small screen.
I get good 3G coverage where I live so the lack of wifi on my DXG has not been an issue.
My K3 has some better PFD support but for the PDF's I have, these all read fine on my DXG and in all cases better than on my K3.
I think we will soon see a software update for the DXG that will include better PDF support, and maybe a few more K3 things.
For me, I'm very happy with my recent DXG purchase.