To be entirely fair, I suspect that the founding fathers would probably be horrified by the number of liberties there are in the USA today. Let's not forget that you're talking about people who kept slaves, followed sexually repressive religions, were almost certainly racist, sexist, and so forth.
You're right that they might also be disturbed by government spying and such things, but I suspect such matters would be overshadowed by their moral outrage at the USA's social liberties.
This is why I feel that appealing to the Founding Fathers is not necessarily a good thing. I doubt the current state of the USA is anything like what they envisaged. Tough. It's no longer their USA. The question is whether the current state of the USA is what the
current population of the USA wants, because ultimately that's all that matters.
The checks and balances established by the founders were not designed to restrict the USA to an unchanging formula based on what the founding fathers wanted. They were designed to prevent any future government of the day from turning the USA into something the people of the day didn't want.
The starting point, thus, is not "What would the founding fathers think of this?" but "What do I think of this?"
At least, that's how this non-American perceives it.