There's a breeder near me that seems to produce some pretty drivey little cavs that do great in agility. Some other cavs, not so much.
I have friends who breed them. They have multiple ADCH dogs, one MACH (and at least one more who is really close there). I don't think they are all super easy dogs to work with - very soft tempered, for the most part - but once they are going, they are pretty much ruling the 12" division. I admit, I've fallen pretty hard for their dogs!