Landis is paying back to his donors by doing more good than he committed bad. I hope. At least he's exposing himself, coming clean. Who is thinking he is lieing about confessing to have cheated all along? Landis is more believable about his own doping than current riders are about theirs. Chew on that for a second.
Giving back more than I stole, that's how I'd do it myself in his position I think and hope. On top of that though, I would work my whole life (boring office job or motivationa speaking) to give all donations back. I can deal with debt, bad mojo. Donations aren't a one-way street per se. No-one just ever gives money back. Donations are based on rust. Violate that, and you should be expected to return the money. Betrayal shouldn't pay.