I LIKE this idea. I like it a LOT. Good insight my dude, that might as well be canon for me. Plus the whole point about choosing to be different is very interesting. Was her choice worth it? I expected more from Liet Kynes too. He was sitting at such a fun power conflux, but then, that's why he died arguably. The Shadout also feels like a letdown when you think about how smart and tough a Fremen has to be to make it to old age. The long life thing I believe refers also to quality of life. Plus if a person can afford to eat lots and lots of spice they are likely influential enough to get murdered as well. Death by involuntary perforation is abundant in the Dune universe.I think her decision to bear a son indicated that she was so unconsciously connected to the BG breeding plan that it was an instinctual answer to finding the Kwisats Haderach.
I would say her choice is worth it if you consider revenge worthy. In the end, a lot of her decisions directly loosed Maud'Dib upon the Harkonnens and the Imperium so in that sense, I'd say hell yeah, kill Harkonnens! I also feel like by the end of the book she had lost a good deal of faith in the Bene Gesserit. She had seen their mistakes through her son's eyes and how they failed to react to a lot of pivotal points. Closing the book on her finals words of "History will call us Wives." left me thinking that she felt a deal of disappointment with the BG's handling of their own end-game. And I think you hit the nail on the head as to why the Shadout was disappointing. You'd definitely have to be pretty cunning to live that long as a Fremen.