I thought there was a discussion about this sort of dynamic/adaptive pricing tactic awhile back, someplace else in FlyerTalk (not Hyatt)? (Couldn't find it.) I know there was a recent WSJ article about Orbitz doing this to Apple users, and I found an old article from Consumer Reports about this sort of practice in general, especially with different browsers. Never noticed it myself in Hyatt...yet. Although, I do notice that sometimes previously "sold out" properties (when not logged in) will display some rooms as available (at extremely high rates) when logged in as Diamond, but I always assumed that was just one of the Diamond benefits of guaranteed room availability...for a price.