The difference is that he is less prone to turnovers which is a significant difference between the two.
I'm not really going to argue with your main points as I tend to agree with them for the most part. I don't know what Gilbert has or could have but at this point, I'm not so set on either of our other two that I wouldn't mind seeing what either he or Keenum have to offer. But I don't see what the coaches do/did in practices.
I pulled the part I did because you are not the only one who brought this up. Yeah - Davis had some serious turnover issues - especially in his last couple of games. But look at who he has played against vs Hill.
Aside from Minn whom they each had an INT against, two of the three teams we've faced with the least turnovers are Denver and San Diego. Denver has a good pass rush and decent DBs but we man handled them in every aspect, played very safe offense, and still only came away with one touchdown. San Diego has virtually no pass rush and very few turnovers. In fact they had 2 total turnovers in the previous five games.
Compare that with the teams Davis went up against. Philly who has the second most sacks in the NFL, San Fran who leads the league in INTs and has the fourth best defense in the NFL, Seattle with the third best defense in the NFL, KC who is allowing the least passing yards in the NFL, Arizona who has the fourth most INTs in the league (one less than San Fran).
So Hill has a good game against Denver but has as many turnovers in one game against a fairly weak San Diego team as Davis has had in any of his games. And I would say from my standpoint at least, that pick by Hill at the end of the game was every bit as devastating as a pick 6 - maybe more. And he had a fumble for a TD.
Personally though I hope for the best with Hill as our QB, I don't see anything that really says to me that he is either less of a turnover problem or a better option for moving this team forward. The eye test? I thought he looked awful yesterday against a pretty subpar defense.