I have a 10mm gun. It, and the rental gun at the range I worked at both had the slides crack.
But it wasn't necessarily "The power of 10mm".
If you look inside the slide by the ejection port, the way it's milled has a horrible stress riser. So basically it'll either fail or it won't.
BUT I sent my gun in, they fixed it under warranty and I had it back within 2 weeks with a upgraded slide and barrel (faster to fix than fitting a new slide alone).
It is BY FAR one of the most accurate guns I have ever shot. I routinely let people shoot it and they always shoot very well with it. Even being a 10mm shooting full power loads it's a pussy cat. Lots of muzzle rise, but even .45 out of a 1911 feels sharper. EAA's in .45 ACP shoot like a dream. I've probably put about 2-3000 round through it and it runs like a champ.
Witnesses also are by design easy to change calibers. They where built in Europe for IPSC and IDPA copmetition where getting multiple handguns is time and money consuming. So they made it easy to slap any caliber slide of and run it.
So far there are slides in .22lr (I have one, works great) 9mm, .38 super, .40 cal (some one makes .357 sig barrels aftermarket), 10mm, and .45 acp.
Here's a link ot a TON more info, and possibly parts and accessories (don't know the status on that though).
Huge EAA write up.