Well after my CZ5 was stolen, all I could get to replace it was a 3D.  I had already tried the 70 and did not really like the digital - I think it's just familiarity with the analog meter after all these years..  Plus I feel that my 70 gives different tones than the 3D.  My 3D seems much more mellow?  Anyhow, if my detector had not been stolen, I would still be using that great old CZ5, I'm sure.
Yes, I am hunting parks and public areas that are old, but are still used (for the most part).  I have tried the advanced mode at some sites, and areas that I have *cleaned* to see if I have missed anything... and all I dig with the advanced mode in these areas is junk.  Therefore, I feel confident I'm getting what's there with the 3D even in salt mode.  
I am not convinced that salt mode reduces depth at all.  Some people claim this, and it may be true with their particular machine, but I do not feel that is the case with mine.  Enhanced mode just seems to make junk sound better.  I run with nothing disc out, so I hear all the tones.  I use my ears first and the meter second.
I was at a park yesterday and did not have a lot of time to hunt.  It was my first time there and knew there was potential for old coins.  I listened for the deep, soft signals - some with bounces and ignored the louder signals that registered at 3" or less on the depth meter.  My first hit was a zinc signal at 5" and I say to myself, indian head.  Sure enough, a nice green 100 year old (1907) pops out.  All the other hits I dug were 4" or more and the bulk were wheaties, the oldest 1912.  No silver, but I'll give this site a good working over and I'm sure it's there.  Plus there are plenty of modern coins 3" or less to keep me busy when I have more time.