This is a feature specification testing just added to CsCheck. FsCheck doesn't have something similar.

CsCheck and FsCheck cover the same sort of testing areas but do things in very different ways. I'd say CsCheck is more complete but I'm biased.

It can be the very best tool sometimes. If you have a property to test, or if you have an oracle, or a brute force method. For example you want to refactor a complex method. Just take a copy of that method in the tests as the oracle and set up a Sample test so that they always agree and refactor away. You can also put a Faster test on it at the same time and prove it's 3x faster say. It's just more robust than a few examples.