Vader Episode 1: Shards of the Past

Talk about something to be exploited. Couldn't you create a "Manchurian Candidate" candidate with something like this?

The discussion at Metafilter referred to the "Stay Puft effect" meaning you might mistakenly think of pleasant things when you're supposed to bring up the bad memories, and therefore the good memories would be erased, too.

Give me your pain.

This makes absolutely no sense to me, unless you are the type of person who remembers one thing and only one thing at a time. I might remember burning myself as a child, which might be nice to forget. But, with that forgetting, will I also lose the memories of mom taking care of me, my best friend walking me home, siblings concerns, and all else associated and intertwined with that memory?
In short, this sounds like a tidy little basis for fiction, but maybe not so great otherwise.