Okay my main TOON (Yeah Sig I know how you love that term) Has all of her EDs at lvl 5 if not completely capped.
Under your proposal one would completely cap out one or more destinies, Go to an NPC prior to reincarnation (or for simplicity's sake just go to Kruz,) and choose a feat. Upon TR the feat remains and the XP associated with it is reset to 0 leaving all other destinies and fate points intact.
I like this a lot. One thought though:
Perhaps EPIC TR should be a different system than HEROIC in that there would be no need to restart at level one if you already have all the past lives necessary for your final build. Or maybe the feat granted prior to Epic TR could be powerful enough be something of an easy button for heroic leveling. That might make completionist a bit easier. Granted, that would be a kick in the teeth to those who really worked hard at getting the completionist feat, but it would likely be a great incentive for folks who wouldnt ordinarily TR over and over to replay all the older content and extend the life of the game itself.