They are, but the price isn't fixed yet, and the delivery date isn't confirmed ;-)
Initial tests look pretty good in terms of being stronger than the standard ones.
CV's are a bit of a minefield in some respects. An alternative for some of the newer vehicles is to convert to the older AUE2522 CV used in the early 90s and 110s as these tend to be much stronger. This does involve swapping a few other bits over at the same time... it's just a case of doing some maths.
The Ashcroft CV is made from a better grade of material than the standard item, and it machined to be stronger.
The other thing to bear in mind if you are breaking joints is that the genuine / GKN CVs are stronger than many of the aftermarket replacements. They are more expensive, but a lot depends on what you want from life ;-)