Kentucky soil is mild like mine right below you. So if you only hunt Kentucky, then ground balance isn't paramount. The F22 has Iron Audio, which is a nice feature. The Delta has a true static all metal mode.
I don't hunt relics, so I would go with the proven Delta 4000 for coins and jewelry. I usually disc out iron, which is beneficial to relic hunting. If you hunt relics, the F22 is a better choice with it's Iron abilities and controls. You can switch quickly between the Artifact, Coin and Jewelry modes in a F22. The Delta requires setting each up each independently. The Delta and F22 are the same process, so a difference in depth would be because of the stock coils and which mode one is in. The all metal mode would be deeper than the 3 presets and 1 custom on the F22. But depth isn't everything, especially when you are talking an inch.
Since FTP has dropped the price of the Delta below the F22, it is the better deal. There are more positive reviews on the Delta than the F22 also.
The deal of the Delta and pinpointer for $279 is the BH pinpointer, which sucks compared to the PPer you have. The Delta for $200 is a great deal and will take you up quite a bit from your Ace 150. Plan on going back to places you hunted with the 150 to clean up deeper stuff, and finding stuff you missed.
