To me, it a no brainer. The 800 has wireless headphones that sound pretty good. That alone makes it worth it. You won't be tethered to the detector like on the 600. Plus it has the wireless module that allows the use of other headphones. From what I read of others who use the 600 , the headphones are not well liked. So if you upgrade to a better set, you negated the price difference.
As for the settings of the 600 compared to the 800, the 800 gives more adjustability and depending on your hunting preferences, the 600 might not do as well in certain situations. As for simplicity, most of the settings on the 800 are the same as the 600 but the 600 has fewer adjustments. So if one can use the 600, the 800 will not be that much more complicated. The biggest difference is that the 800 has more tone adjustments like tone break, tone volume and tone pitch. These adjustments are better for setting up to get the sound effects you like. This is nice in the trash as to make the coin tones stand out.