Enjoy your GTI 2500!
Humble opinion here ... You have one of the finest detectors going anywhere. I've had a dozen units, including "top of the line" from several manufacturers (or so they say). I wouldn't trade my GTI away for anything, now that I have come to see what it does.
Suggestion: If you don't have a test garden, go ahead and toss some coins on the ground. On the surface will be OK for this test. Also toss out a couple of bottle caps, some foil, pull tabs, and some larger pieces of junk (larger than coins). As you are swinging your coil to pinpoint each target, raise and lower your coil to different heights, say from six inches to two inches or so above the target. Note how the GTI shows both the size and depth for each target.
Yep, I know it's just an "air test", but you'll see how the target sizing works. The GTI will be accurate for buried targets -- both the depth and the size.
Once you see how it works, you'll save a lot of time in the field. You'll find more time available for searching new targets, and less time wasted in "digging and wondering" what's in the hole.
You've got a great machine. Enjoy it! Let us know your experiences with it.
Cheers,
Joe