Ant -- I hit 8" deep silver in my test garden. I don't have a video of a 7" recovery, but I guarantee that, at least in MOST types of soil, a 7" coin is NO PROBLEM. And I mean NO PROBLEM.
I buried 24 coins in my test garden a year ago, both silver and clad -- measured with a tape measure. I have 6" coins, and 8" coins -- no 7", but I can hit both the 6" and 8" coins with the Bug. The 6" coins are EASY; the 8" dimes and pennies are also easy targets, when the soil is damp. When the soil is VERY dry, as in drought conditions, the 8" dime/penny is a bit less consistent in disc. mode, a little more "iffy," but still an easy target in all-metals mode. The 8" quarters are easily seen in wet OR dry soil. I don't know if this helps you or not, but these are measured depths, in moderate soil.
I will make a statement here, that I will stand behind 100%, and it will probably shock alot of people, but it's 100% true, based on my experience. My main "deep coin hunting" machine is a Minelab Explorer; as an owner of both, I have arrived, through testing and experience, at the conclusion that the Gold Bug Pro is just as deep -- let me repeat that, JUST AS DEEP, on coins, as my Explorer is, in my soil. In my test garden, the coins are buried at 2-inch increments from 6" to 12". There is NOT A COIN, in that garden, that the Explorer will hit, that the Gold Bug Pro will not. While I prefer the Explorer when I'm purely coin hunting, for a few reasons, I believe the Gold Bug Pro is a WAY UNDERRATED machine, in terms of being a coin shooter; it is just as deep, and IDs nearly as well with depth, as any other machine I've tested, in my ground conditions.
Steve