I own an ACE 250 and have used it it alot in the past. I can tell you that you will find all varities of coins........clad and silver. The silver ones have to be there. I can also tell you that you will not find all of them. Not to start a debate here, but you're not going to find every coin with an ACE 250 simply because the coin is below the coil. The truth is that you'll miss some targets with a machine like this. Some will not be possible for it to detect. Trust me. Anyone here can try using a 250 for a year and then something like the Explorer I use now and you'll see what I mean. I always go back to the same park that I could barely grab one coin out of with the 250, where I can go back today with my Explorer and pull out 4, 5, or 6. I'm not bashing the 250, I think it's a great entry level machine, but it has its limits and it's not simply a matter of being over a coin to find it. If I had to compare, I would say that the 250 can see 1/6th of what an Explorer can.
Best,
Ricardo