I salute you as it is a brave and difficult decision, one it has taken me a while to make for myself also. Good luck with it; one positive of course is that somewhere somebody else will be enjoying the bikes as much (possibly more) as you have.
The only thing I would say about the Zaskar and to anyone out there thinking that it should be kep for posterity is don't just keep it based purely on the act that you've had it from new, there needs to be more to it than that in my opinion. I owned a 1994 Marin IFT from new and when I sold it 2.5 years ago on here I saw it go to a chap who appreciated it far more than I did, made a fantastic resto, and upgraded the stock parts very sensitively and made a much better bike out of it, probably got more enjoyment out of it than I was getting at that time, and probably gave it a whole new lease of life. I replaced it in my life with a "better" bike, one that I could never afford to own or even have borrowed to see if it really was that good back in the day and have never looked back on that decision. I don't need the bike to remember how much I enjoyed riding it.
That is of course my opinion; not trying to sway you at all but just a comment on the rationale used to decide.