I think it is a little too much corroboration. And Davila's "statement" is one that was written in November 2006 and the paragraphs that reference it do not include reference to an exhibit supporting it. I don't buy into this one, unless I see statement or testimony from Davila, or a report from Sanchez written sometime before June of 2005. (Yes, I'm a skeptic).
I laughed when I read the Agent's note about the shotgun--it was overkill to sell one possibility, the one they wanted to write. I can think of plenty of ways to have my hands on the barrel without pointing it straight at myself. Again... these are C.Sanchez's words (and another agent), not Compeans. I want to hear his testimony.
The section in question was about a series of interviews held with Davilas before the trial, but you are correct that the report doesn't have an attachment showing a written statement signed by Davilas. I would hope there is a recording of the discussions somewhere that would contain this information, but I haven't seen it.
But you are correct. If we assume that Sutton is crooked, that Sanchez (both Rene and Chris) are crooked, that the defense attorneys are idiots, that the 3 other BP agents and their supervisors are crooked, and that they are all willing to commit multiple criminal offenses in order to put two BP agents in jail, then we could surmise that they fed Davilas the correct words to say to match the testimony of the others.
Of course, they could also plant evidence and bribe the jurors.
Problem is, once you assume this stuff is a grand conspiracy, it's a self-fulfilling theory, because any "proof" of guilt is obviously planted evidence.