I teased all the teams this week in my 14 point round robins. Except the Seahawks (Carroll factor), Broncos (Tebow factor) and Saints (Payton knee injury factor).
You've identified the two sets of rules on teasers. For those that don't know...
"Las Vegas" rules treat a tie+loss (ir tie+win) as a no-action, with ties reducing if there are more than 3 legs.
The books that follow "Las Vegas" rules for teasers is fairly small - so few, that I actually refer to "Offshore rules" if a book treats a tie+loss as a loss.
Teasers are profitable for players - many pros play those as their bread and butter. Vegas got clobbered last year, and consequently changed a lot of their payouts for the worse. Even playing against "Offshore" rules, the player has a monster advantage. I don't see it as a problem, as long as the rule is clearly spelled out.
One other observation - "Offshore" rules don't hurt professional players nearly as much, as they tend to play 3 or 4 teamers a lot more than 2-teamers.