I have the AT Pro & it has great depth, ID, & separation. I used it in the super easy STD mode, coins program, sensitivity 7 of 8 & manual ground balance. It was very quiet & stable, until I got a pretty loud beep that said about 8" & ID bouncing only 80-85, repeated high tone. Dug down 7" & there was a clad dime.
I detected this park maybe a couple hundred times & have competition. Dime probably lost in '70s or '80s. I had iron totally rejected (40). At iron rej 35 I got intermittent signals from rusty bottlecaps.
The accuracy amazed me as when I used the Ace 250 I couldn't get in ground dimes to ID accurately beyond 4". The AT Pro can go to 10' underwater, a bit over 3lbs, not bad 4 AAs for economical searching. Air test STD mode dime high tone & solid at 10".
Sadly, the accurate visual ID is small & hard to read. Even in STD mode, the separation with stock DD coil is above average. The disc can be turned up high with seemingly no loss of depth.
The AT Pro is loud audio at all depths in STD mode & in Pro mode it is modulated audio so dime at 10" is whisper. There is some background noise in this mode, but users report things like a coin detected under a rusty nail. Dime at 10" in air was back & forth between mid & high tone.
Zinc cents bounce back & forth between mid & high tone. A copper penny shows in low 80s & upper 70s, so it may be possible to tell them apart from dimes, at least in some soils. I want the copper pennies worth 3 cents, but maybe not the zincs that may have pieces missing.
I also have the Teknetics G2, identical innards to Fisher Gold Bug Pro DP. $699 retail but bought it used. It has fairly quiet audio, there is always noise in background as it beeps softly on ground minerals, which I think is why it is so good at picking things out of iron. On my 5" deep planted dime, the ID bounces between dime & zinc. Single 9V battery.
The G2 doesn't have notching, but probably not needed. 11" DD coil. It has modulated audio, so a dime in an air test just whispers at 10". The visual ID # is large & the ground phase reading is easy to read & tells you when the ground has changed, so you will know to rebalance for best performance. Best wishes, George (MN)