I looked for a 1%, 2% or 5% choice on the poll. Seeing none, I rounded to zero.
My main concern about cheating would be a phone line or ICQ when playing in tournaments. You say these events aren't important enough to make people want to cheat?
At OKB, there was a full blown scandal about teams cheating in ladder matches. Not even Lehmans were involved. The only real way they stopped the offenders was going through the play records. Jeff Goldsmith has a link on his site about this incident; I'm too lazy to provide a link
At one of the clubs I played in a husband and wife couple were permanently banned by the league from ever playing together again. They offered to show the league 'how' they cheated in exchange for being able to play together again. The league refused. One of the famous hands was a lead away from Kx against 6N when pard held the cashing Ace. Don't ask me why they did it, I'm not a psychologist.
Now your talking about masterpoints in BBO tourneys, and (hopefully) some swiss and KO's awarding (a lot more) points.
I'm not concerned about memory aides (keeping track of tricks, etc.) while playing on line. You can't stop it, and a decent player doesn't need it anyway. I'm not worried about references to convention cards or notes either.
Hesitations, incomplete disclosures, etc., are easily handled by a director at the table.
The 1% are out there, and policing will have to be a priority if online bridge for anything but fun is taken seriously.