Having just gone through a comparison of a DW3 and a D500 after the Chicago meeting, I purchased the 3Shape. I was really conflicted and did both with TeamViewer sessions. I really liked the multi die scanning of DW, and the ease of getting things scanned in. The thing that separates 3Shape is the design and end product. DW is more "graphic" orientated in it's right click pop up dialogue boxes which then take up room, is more like running Windows OS, it's more clicking and ticking. All the 3Shape options are right there on the edge of the screen ready to click or slide, as has been mentioned in above posts.
When I was doing the TeamViewer demos, during the DWs demo, we came to a screen that went black in the background, we did something else, and I don't know if we went back to the same screen, but the background was black again. I asked if it was a glitch, and was told yes, I asked how long it's been around, and was told, "for awhile". I know they came out with a better tooth library, and some other updates that I didn't get to see at the time, so I can't say on that front what improvements it made.
My 3Shape PC did come with Windows 7 Ultimate 64-bit, a i7 3770 3.4 GHz processor, and 16 GB of RAM. The graphics card is good, the HD could be a bit bigger (233 GB),but I'm happy with it
I'm a one man lab, who doesn't do implant bars, so the D500 was fine for me. (I do have the Premium Software, and the Implant module)
edit: added HD size.