I got the concentric for the same reason as trueblue, it has been widely recommended here. In trashy areas where there is so much under the standard coil that I had trouble isolating things with the Tejon, the 5.75 makes a huge improvement. I have not yet hit the issues with the concentric trueblue talks about, but I suspect he has a lot more Tejon time than I do.
The only widescan coil I have is the 12 x 10. With the 12 x 10 pinpointing is not quite as accurate as with the standard 9 x 8 concentric or with the 5.75 concentric. The 12 x 10 widescan pinpoints at either the toe or heal where the two D's come together, would expect the same toe or heal pinpointing with any DD.
I have not tried to set up specifically for lead or brass. That said, running with primary discrimination at just the low side of foil, lead solder droppings and bullet shells of all sizes hit hard with the Tejon. I have one area of my front yard that I had thought I had cleaned with other detectors, the Tejon found lots of solder and a couple shells and they were not little whispers from the Tejon.
tvr