1. option key is not a path - this is confusing advice to end users. Please use the standard Mac URL of slashes and folder names to describe paths.
2.this convo seems to be confusing the idea of the number of pics that the "pic" screensaver can use (such as the Ken Burns type) with the number of actual screensaver files (known as ".saver" files in 10.8) the OSX Screen Savers folder can hold. It appears to me the OP's question had nothing to do with the later.
3. my reason for visiting this thread at all was the hope of determining the actual file limit of the number of pics that the Ken Burns screensaver tool can actually process. Its documented on the internet that Apple TV cant handle very many pics, and one might reasonably assume 10.8's implementation of the process has a similiar capacity. If anyone knows please advise ! I love being able to show off pics via the Ken Burns OSX screensaver !