I agree that the truth is often simple - it is greatest truth of all times in my opinion.
Yes, one should asks himself would really Rudolf live that long. I agree. But we can never know.
As for Mary's farewell letters, in fact I doubt that they were 'recently, newly discovered' -- several fragments are reproduced in 'Idol's End' by Claude Annet.
Also, reading about Mary Von Vetsera, I see nothing but 17 year old girl, young, naive fatally fallen in love with Crown-prince. Seriously. I can bet she was ready to do anything for him.
On the other hand, I can't decide what to say about Prince - he seriously had hard life burdens making him desperate and unbalanced.
In history, I love the chronology for most : So Prince arrived at Mayerling Castle on 28th January 1889 at 15:30h, and Mary on that same day but several hours later? What fascinates me, policies and spy-agents were controlling Prince's steps months earlier from what I have understood. So they knew precisely every his step.
Also, is possible to know whether the pair met in early November of 1888 or earlier, in the spring of 1888 (April 12th) at Prater or elsewhere as described in Annet's (romanticized, I must admit) book?
I wish people who witnessed the whole events said more in their testimonies, memories (such as Marie Larish or Bratfish, Loscheck and Hoyos) .
Also, one question that strikes me - how many bullets were fired...? One, two? Some accounts say even five that were removed from Mayerling's bedroom. If there were more than 2 fired, one has to ask were those fired by Prince. It is just my mind that ask logical questions, never mind.