YES, Smudge, zincs you'd miss, as they hit in the mid to upper 70s, and nickels -- which hit around 58. Copper pennies are, though, as you say, above 80 -- at around 83.
While these units in some soil may not be as deep as an Explorer -- I will surprisingly say that my GB Pro with 11" coil will hit coins ALMOST as deep as my Explorer will, in my soil. In my soil, I just don't get quite the depth that others do with an Explorer; here, a 9" deep dime is a fairly tough dig here with the SE Pro. But, the GB Pro is neck and neck, in my ground...believe it or not. NO DOUBT, in mild soil, an F-75 LTD or SE will be a deeper unit. But...my GB is NO slouch, in the depth department. It amazes me.
Anyway, I agree with you...it is not the DEEPEST of all machines, but it will "hold its own;" besides that, it does have some things it does VERY well (mitigating EMI, very accurate ID with depth, light weight, and the ability to set your "tone break" being excellent "positives" with these units).
Steve