. . .
Lastly, you are legally responsible for whatever your expert puts down on the tax return. That is why you sign it.
True, but my rationale for hiring a tax preparer has been that if the IRS has any questions (or worse), the preparer deals with it, not me (at least not directly). This has happened only a couple of times in my life, but each time the preparer spent a number of hours at no extra cost to me dealing with the IRS. Whether the preparer charges for additional time spent may depend whether the preparer offers that sort of guarantee and what the issue is that caught the IRS's attention. That said, as my finances continue to become simpler--no longer any rental property or business income--I will probably do my taxes myself in the coming years.