I think the vast majority of resale transactions go through without a hitch.
But my experience here on the DIS is this: IF there is going to be a problem, it will occur with Fidelity. NObody else has the problems these folks have...NObody.
One strategy some have used successfully is to go through another broker for contracts you see on Fidelity's site. TTS doesn't co-broker, but the other two frequently-mentioned firms do. Using a co-broker doesn't cost a cent, and the other firms seem to be more diligent and competent than Fidelity.