I had the opportunity to buy either, money wasn't an issue, and there was no hesitation for me...I went for the 800.
Why, not because I hunt for nuggets or really wanted or needed the WiFi headphones or WM08 module but because of the extra settings possible.
The expanded range of a few, the user feature that can save custom settings and most importantly the extra tone adjustments available on the 800 that were not on the 600.
I use all data when I hunt, tones, display and target behavior and it can all change when you use different settings.
I had no idea what settings would be the absolute best for my dirt, still don't, but I am a huge tweaker and found using others sometimes using some out of the box settings can have great advantages in difficult conditions so why limit myself in any way?
I would much rather have all setting possibilities available and not need them then find I need them and not have them.
I might not need the 20 and 40kHZ frequencies to hunt nuggets but they might have advantages in combating my mineralized iron infested devil dirt.
The only way to find out is to try.
I can hear all the tones the 600 has but who knows if the greater adjustability of the 800 tones might make a difference in what I can perceive, notice and find?
Again, the only way to find out is to experiment and try.
If money was a huge consideration I would have bought the 600 and would have been satisfied and from what I have seen so far I can well recommend the Nox, any Nox, for many situations.
For me a major thing was worrying about the what ifs...I did not want to regret my decision immediately or anywhere down the line like, ever.
What if it turns out using 40kHz or either if the two beach settings had some major advantages hunting in my iron infested sites?
What if one particular tone setting/combination was much better for me to deal with the massive masking problems I encounter every day?
What if I read about some sort of great settings some other 800 owner hit on that worked tremendously on pop tops, pull tabs or any other trash problem I can possibly come across that I could not replicate on a 600 if I chose that one?
I tell you what if...nothing but regret for me then and in the future if I went that direction when I knew I had the choice to go either way.
In normal nice soil I am not exactly sure if I would have even thought about buying any Nox, I hunted in that kind of dirt for a couple of years and everything worked, worked easily and worked well.
Now that I hunt in the mineralized SE in a particular area of the country where we are so lucky to have so many extra major issues an challenges this tool, and the way it works here, seems to be special.
Again, if money is an issue having a 600 is better than not having any but if it isn't so much an issue those extra couple hundred bucks is a no brainer....why limit yourself when you don't even know the capabilities of either one in your dirt and the conditions you hunt in?
To repeat...I would rather have something and not need it than find I need it and not have it.