Hi Bogger,
Goldwright's comments above are spot on, I have both the 5000 and the 7000, that I've had since they were released, the 7000 will certainly find gold that the 5000 will miss,rough reefy stuff similar to your avatar.
I keep any gold found with each detector in different containers and by area in which it came from, comparing the two lots of gold the 7000 collection is for the most part rough and the specie count for the 7000 is way, way ahead of the 5000; the 5000 collection is for the most part solid and well worn pieces, the 7000 does well on this type of gold also.
Having the two detectors, it's handy to cross check various types of gold; on one area that has been well flogged with 5000's and found difficult to work due to the hot ground and with no significant finds; the 7000 is quite the opposite in that it turned out to be a very worthwhile area giving up some nice pieces.
While the 7000 has fewer settings to manage it has taken us, (there are three of us that usually detect together with our 7000's)the best part of twelve months to fully explore and learn the finer points of the machine, nothing major, just fine tuning and listening to the various signals from a year or so's worth of different gold and junk targets, quite different from the 5000 for the most part.
If for some reason I had to part with one detector the 5000 would be the one to go, they are great machines but he 7000 is a lot more versatile; like most 7000 owners, the soon to released 19 inch supper coil will hopefully add yet another dimension to the 7000.
Hope the above is of some assistance.
Cheers, SinHof.