If you need more rationalist MLP fanfiction in your life, I'm 5/6 of the way through writing mine and could use feedback. It's intentionally somewhat less rationalist and more fanfictiony than either of your examples.
(I'm aware of the irony of posting this link in this thread, but I figure most posters who are bored by all things pony will have stopped reading the thread by now.)
I just started the chapter "Loyalty" and so far, I don't have any feedback so far other than PLEASE keep writing. I mean, I've read things about Immortality/Death before, but so far this is really tugging on my heartstrings.
Edit: I couldn't stop reading and I ended up reading all of it in one go. I still don't have any feedback other than please keep writing.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.