We trusted Grassley and he delivered. I doubt we'll ever hear Q say trust McConnell, so at this point I'm not sure who we have left in the Senate that has any power here, but I'm trying to keep an open mind.
Seconded, though I think Grassley's purpose has been fulfilled by getting it out of committee. I shudder to think about trusting McConnell to do right by us on this.
Problem is we can't trust the FBI yet, and even if we could we certainly wouldn't trust them to complete a thorough investigation within a week.
They will leave cracks in their report, which dems will slither right through which will either reinforce doubt for some, or will force debate about expanding / delaying the investigation.
At that point, they may as well turn it over to Mueller.