For sure try it with the stem and coil positioned to face you, it makes it all so much easier. Seeing the display screen and the targets as you swing them across the coil helps your brain relate everything. You can try coins, rings or trash. Swwep them flat, then tilted or on-edge and in combinations, all the while changing sweep speeds, depth and centering beneath the coil to simulate various what-ifs. All the concentric coils I've checked exhibit several "zones" of poor ID. Sweeping random targets in-ground won't quickly reveal where those false ID zones are, but some time spent on the bench will.
I have a 2200 here. I like it and think it's as deep and accurate as my Time Ranger in it's "standard" motion modes. It looks like the 3300 adds a no-motion pinpoint that is absent on the 2200. That, plus the manual ground balance are the major differences between them. For the way I hunt, a no-motion mode, even if only offered as a press-and-hold "pinpoint" button, is a very worthwhile addition. I'd be interested in seeing how the manual GB know works and which modes it affects. The Time Ranger has a ground balance, but it is under machine control, and not available for "user-tweaking" as the 3300 appears to offer.
-Ed