that may possibly hit as mid tone on the 6a. Remember, the 6a only has THREE tones. Also, remember that some of those types of targets MAY also hit as high tone on the 6a as well.
Enhanced mode on the 3D is a unique feature that as explained by the designer, uses the ground matrix and older coin composition to bring these types of targets up into the high tone area whereas it may hit as mid tone on the other CZ's like the CZ5, CZ6a, CZ-70 Pro.
Most all of the US silver coinage will hit as high tone on both units, so no worries there.
Last...the CZ's are not complex at all and probably one of the simplest units to use. Ground balance, don't run the sensitivity too high, run in discriminate mode 0 so you can tell the difference between iron and non-ferrous targets, sweep slow to moderate and dig all repeatable mid and high tone signals that hit from multiple angles.
The analog CZ's are by far my favorites. No programming, can tell exactly what settings you are running just by looking at the face plate, increasing the level of discrimination does NOT affect depth, modulated audio if you want to run it that way, can hunt salt water beaches..the list goes on and on.....just great all around units to have in the arsenal.