Some thoughts: While dna and forensic evidence is extremely important and necessary in the legal sense, a grasp of the psychology of a crime goes a long way toward making one a "believer" or not ....In any case, I find the psychology of motive massively important...
I am aware that statement analysis is something which cannot be as "scientific" as blood evidence or dna, I do think that there are a couple of things in the email which do point toward a scenario and how it developed:
As I have mentioned many times, the fact that the statement analysis showed that something "out of the ordinary" probably did occur after lunch on Nov 1, prior to "saying goodbye" to Meredith has always made me ponder that some resentment carried over into the evening, making them return to the cottage. I also felt it was telling that in her email, Amanda did not write, "Meredith still had her Halloween makeup on from the night before" - what she did write was that the costume was still dripping blood. Imagine having resentment and an altercation, and the person has blood dripping from their mouth. It might put an idea in your head. Especially if one had a few problems with jealousy, envy, etc.
*And why is it that no one has thought that the altercation (begun early in the day, and carried on later) might have revolved around Meredith "stealing" her job, and her popularity at LeChic? It might explain the accusation against PL too.