I'd say of those organizations (FBI and Stasi)...they were and have been both competent and incompetent, it all depends on how you look at it. Incompetent in the details. Competent in that they usually succeeded in putting someone "out of business" when they wanted to. They generally achieved their objectives. This is typical of the largest and most powerful bureacratic organizations. They succeed not through efficiency, necessarily, but through brute strength and unwavering purpose. The Stasi finally failed when the very system that they served itself failed, but not before.

There's a saying: "I fought the law and the law won."

Why? Why does the law win? Not because the law is necessarily efficient or wise or particularly competent. No...but because the law is BIG. It's big enough to outlast and crush any private individuals who may challenge it...or get in its way.

People would find this true, on an individual basis, if the law enforcement agencies and intelligence community in the USA turned their strength toward serving a quasi-dictatorship, just as they have found it true in any number of other countries.

There would then be a number of choices, such as...

1. Go underground and resist clandestinely. (very risky)
2. Flee the country. (always an option, if you can find somewhere to go)
3. Join the forces of oppression (many would opt for that).
4. Try to avoid getting into trouble, be a good little worker, and keep your head down. (even more would opt for that)
5. Engage in open resistance and even violent insurrection. (Good luck! Be prepared for a short life with a violent ending. But, hey, you never know...sometimes such revolutions succeed.)