I watched part of the Anita Hill hearings, during the confirmation of Clarence Thomas, in 1991. I watched some of the Oliver North congressional hearings, part of the Iran-Contra scandal, in 1987. I've watched parts of various Senate confirmation hearings over the years and snippets of the Benghazi hearings. From my personal viewing experience, I can say I don't blame Christine Blasey Ford or anyone who hesitates to testify before Congress.
I cannot recall ever seeing a congressional hearing that was conducted fairly, professionally or in good faith. Every single one I have watched, whether briefly or at length, was a parade of grandstanding, bloviating, pretending, accusing unfairly and defending without justification. That's the members of Congress I'm talking about. Witnesses are frequently (not always) frank and straightforward, but it doesn't matter. They are never listened to. They are props for their interrogators to manipulate. Each member of congress has an agenda and usually at the top of that agenda is making themselves look good, or what they think looks good, through speechifying. They exhibit zero interest in the truth, whatever party they belong to. It's really a depressing spectacle, and it's always the same. Sometimes the congressmen and women pretend to be sympathetic to the witness, sometimes they pretend to be outraged; sometimes they pretend to understand perfectly, sometimes they pretend to be confused. They are never, ever sincere. It's a grotesque show that displays the very worst of human nature.
So if Ford or Bret Kavanaugh or anyone else expressed doubts about testifying before Congress, or refused to do so, my feeling is: They have every reason to say no.