Still works as of 10/16/11.
Completed game on easy with "bad" ending.
Went to dashboard.
Went to game, went to continue.
Last checkpoint loaded, changed to Ranger Easy.
Exited out of game properly.
Clicked continue, checked to make sure was on Ranger Easy.
Completed game with "good" ending.
Got both achievements.
Did same for Ranger Hardcore. Used good ending again and I still got it.