My experience is that the coins don’t crack when they’re rolled out
provided they’re properly annealed. They do however tend to retain a
"ghost image" of whatever was stamped on the coin even when it’s
rolled down fairly thin, say 1mm. I’ve had success getting rid of
that “ghost image” with some minor filing or sanding. It may be
possible to even just polish or lap it away with an agressive
compound but I’ve never tried that. It’s been a little while since
I’ve rolled out a coin like that but as I remember it the silver was
pretty good, no voids or anything as you can sometimes get when
you’re pouring your own plates in an ingot mold.
At the time of wirting silver is at $16.73 per oz.so either way,
it’s a relatively inexpensive experiment and the worst case scenario
is you have some silver to use in your next casting or any other
number of projects. Hope this helps.