Dang, I used that exact search term, and kept getting current stories about Spanish citizens and the like.
OK, I think that I understand enough to understand that no one really knows what is being collected or how it's being used. If we did, then I might be willing to draw some line somewhere based upon that information. And, that line might involve violating certain rights, in order to provide security.
However, before I'm willing to take any step in that direction, I would need to see crystal clear evidence that such an invasion would provide security. In fact, I would want to see proof that it has done that, since it appears this is already being done. And, even then, I might not be willing.
For instance, if the NSA could show conclusively that 4 separate 9/11-type events have been thwarted because they listened to a US citizen talk to an overseas person, then I may (repeat "MAY") agree that the violation is warranted.
But, I don't feel that there is any way to prove that it is. So, baring that type of proof, I have got to fall back on my Constitutional principles and conclude that a violation of rights is not warranted.