The ACE 250 is a great entry level machine, quite possibly the best out there. The 1500 is another animal all together, for sure it'll go deeper and do more in an experienced users hands. All machines will find gold and silver, but as others have said, it notches in all over the spectrum, especially gold. When entering the hobby, keep in mind that it is a hobby and have some fun with it, spend the time learning the machine you choose and celebrate your successes, how big or small they may be. Finding gold with any detector is an art, although all machines will find it in the trash, knowing which trashy signal to dig and how to best invest that digging time is hard to explain to a new person entering the hobby. When you really, and I mean really are in tune with the machine in your hand, and you have great ears and pay attention, there are little clues that will give away those "golden" targets. As you find more and more gold, you will know what I mean. Way too many machines are gathering dust in closets because the owners expected instant success, keep it a hobby, learn as you go, be satisfied with your finds and when you've logged hundreds and maybe thousands of hours in the field you'll be more consistent in finding gold. Make sure you have some fun and get some excersise along the way.
Craig