Code P0430- 2001 Boxster 2.7L

[eiblanco]

First post to the Board, thanks in advance...

I have a 2001 Boxster that just gave me a check engine light. I took it to Autozone and an isolated P0430 error code popped up. I have no other problems with the car, perhaps a minimal occasional rough idle. I read all there is on multiple boards on this error, and it seems the consensus is that the O2 sensors are fine and that it is an isolated catalytic converter issue. Now, I have several questions:

1) Could this still be an O2 sensor problem? I have yet to reset the code, and will see if it comes back. If so, should I even bother to change them? It seems that they have a life-span of 30,000 miles? Is this what most people experience?

2) If it does end up being the cats, do I replace both of them, or it usually one or the other? That is do I change both the primary and secondary cats?

3) Has anyone had experience with used cats? I priced them and there are FAR more reasonable than new.