I haven't read the thread yet, but to answer the op's first question, I'll say no, unfortunately manticore won't do that, neither for tone and probably even less for 2d, since I've seen in the French video he put a coin on the edge in the iron zone..
I dig about 2000 pulltabs a year on my beaches, that means there are probably tens of thousands of them, and at all depths.
already, personally when I drink a drink I don't remove the pulltab, so I don't understand those who remove it, the solution would be to prevent the pulltab from being able to be removed from the drink And I hate these people who throw them on the beach, but the Andalusians have the annoying tendency to throw everything on the ground even if there is a trash can less than a meter away...I was even told that some people throw pulltabs in certain places on purpose to piss us off
so I dig a lot of pulltabs in different states and which are all over the gold range, sometimes when I'm tired and tired I leave 13 id sounds on the nox but yet I've already dug several 18k rings at 13 in telling me before "oh again a pulltab" and of course no way to differentiate these rings with a pulltab whether in the ground or in the air
of course we can wait for the ocean conditions to sort the pulltabs and the gold but it is not frequent, if I waited for these conditions, I would hardly go out to detect
So I doubt that manticore will help us on this subject