I wrote my reply before I saw this posting. I see you have a lot of experience. I also have done the Everest and Torres del Paine trips. Paine I did solo, backpacking, but of course, as you know, there are lots of people on that route and the elevations are pretty low (though beautiful of course).This is much more remote and a much higher elevation.
Everest I did teahouse trekking, with a porter. Did you do it solo carrying your own backpacking gear? That would be a real grunt! The highest I ever carried my own was over a 16,000' pass in the Cordillera Blanca, but it was only a 3 day trip, not doing it day after day.
I'm happy to chat with you about this, and I also would like to get some up-to-date info on Torres del Paine, as I am planning to return there next winter and my other visit was 16 years ago, so my knowledge is not recent. However, in general, you'd probably be better off posting questions and researching on the Lonely Planet Thorntree Forum. This forum here mostly has a domestic US backpacking focus