I dont know how many pages the report it, but what gets sent to the dems will be "No" on page 3, and "Collusion" on page 17 and the rest all blacked out. So basically useless. I dont think the president should ever see these reports first. Should be sent right to the house/senate/public in full. Its like a murderer telling the judge hes innocent because he gets to decide what the judge get to know.
Based on my assumption that there is some definite dirt on say Trump / his admin in the Mueller report:
Mueller has a rep of being incorruptible and doing an honest and thorough job of what he was told to investigate. I find it highly unlikely that he and his team spent ages investigating everything thoroughly and then not anticipating that the GOP / Trump admin would try to bury the report in the event it says something they don't like. Ergo, IMO Mueller (and/or one of his team) will have decided to draw a line at the point that they are ready to intervene (e.g. leak the report).
IMO it's unreasonable to think that people investigating corruption at the highest levels of government are just going to say, "well, if they want to bury it, that's all there is to it!". I don't know whether leaking the report in the traditional sense (ie. anonymously) is the best counter-tactic because the veracity of the leak would be the obvious thing for the GOP / Trump admin to question.
What would happen if Mueller just went to Congress in full view of the cameras and dropped the report off with them? Perhaps a redacted copy from a security (say protecting confidential sources) perspective, but nonetheless it would be a statement saying that the copy he dropped off is untainted with political bias.