Charles Garrett once told me that it was his goal to put as much useful technology as possible into a $200 detector. He succeeded.
(Okay he didnt tell
me that - but he did say it!

)
Is the Ace 250 the
best detector for all situations? No. There is no such thing, to be honest. What it does have is all the user features you could need in most situations in a lightweight, user-friendly and affordable package.
But, ole Charles didnt stop with gadgetry. The Ace 250 also has plenty of depth "punch," excellent target separation and a fast target response - quite possibly the three MOST important features of any detector. At any price.
And just so you dont think I get paid by Garrett to do all this slobbering, there are some quibbles with the Ace 250, too.
1. The Pinpoint is mushy, not well defined. It is probably the one thing most complained about by users.
2. The headphone jack is in a weird location, placing the cable smack in your way, all the time.
3. It is VERY sensitive - and the newbie isnt warned about this.
As to your question: "10" on a dime ... in sand?"
I say very likely. This goes to the sensitivity issue. In clean sand without trash or minerals, you could easily run the Ace 250 at maximum gain (sensitivity).
Under those conditions, you would not get the bonking and boinging you might otherwise get in a more hostile search environment at high gain settings.
This would probably allow you to just hit that dime.
BTW, whatever digging tool you are using, get a file and make some marks on it at inch intervals along it's length. Then you have a field expedient ruler for making depth approximations.