Ronk --
I do not think you have to worry as much about "limited depth" on silver and clad as you may think.
I can hit 6" to 8" silver and clad coins in my test garden with NO PROBLEM, with the 11" DD coil.
I think one issue is, shallow targets are SO crisp and sharp on this machine, TOTALLY different from the soft "zip" of a deeper target, so it's easy when hunting to get used to the loud, crisp report on shallow targets and forget to pay attention to the softer sound of the deeper ones.
SOME of the early-run GB Pros had a depth issue with silver coins. Not so, on the V4 Gold Bug Pro software (or the G2's software).
YES, more depth is possible in all-metals mode; I can hit coins deeper in my test garden in all-metals mode, but still...that 11" coil, running in disc. mode, will yield you 6" to 8" coins easy, if you listen for the softer tones...
The 5" coil is more limited in depth capability on coins, but good for use in trash. In cleaner ground, that 11" coil will hit some pretty deep coins...
Steve