I think Newcomb's problem would be more interesting if the 1st box contained 1/2 million and the 2nd box contained 1 million, and omega was only right, say 75% of the time... See how fast answers start changing. What if omega thought you were a dirty two-boxer and only put money in box b? Then you would be screwed if you one-boxed! Try telling your wife that you made the correct 'timeless decision theoretical' answer when you come home with nothing.

You can't change the form of the problem like that and expect the same answer to apply! If, when you two-box, Omega has a 25% chance of misidentifying you as a one-boxer, and vice versa, then you can use that in a normal expected utility calculation.

If you one-box, you have a 75% chance of getting $1 million, 25% nothing; if you two-box, 75% $.5 million, 25% $1.5 million. With linear utility over money, one-boxing and two-boxing are equivalent (expected value: $750,000), and given even a slightly risk-averse dollars->utils mapping, two-boxing is the better deal. (I don't think TDT disagrees with that reasoning...)