Hi J,
One of the good things about having a T2 is being able to map the ground mineralization of my sites. Yes I do have alot of mineralization in areas runing mild to heavy. More mild in the valley, growing greater as I move up into the Heights.
In the valley, the manual vs. fixed ground balance isn't really needed. In the Heights I think it makes a big difference. Especially since up there there are various soil types all in one location. You have the base dirt which is hot all on its own, then you have the fill dirt that is brought up to grow grass on, then you have heavy mineralized sand dug up and put into playgrounds and such. In those areas, I find the ground balance necessary. There are a number of playground up there that will wrap quarters into the iron range on my DFX just because the sand is so bad. In those places you can balance and hunt quiet in all metal until you cross a soil line, then the thing will scream at you until you re-balance.
Do I really need it for what I typically use it for, no not really. Most of the stuff in the Heights only sinks to the base of the fill dirt. Which is usually only 3-4" deep so there aren't to many deep targets very deep up there. Then when I move down into the valley, it goes coil depth + pretty reliably.
But it is nice to actually balance to the ground.
DFX phase reading in the worst of the Heights so far = 95.7 (quarter wrapping ground)
T2 ground balance and Fe3o4 reading of same = 92 and .3
T2 ground balance and Fe3o4 reading in the valley = 83 and .03
Hope that helps.
Mike