Well, I mean I'm not sure how anyone can really answer that for you. That is totally up to you and how big a deal it would be if your new system crashed and how you would handle that. Personally, in the use case you are describing, no I would not hang on to the old one. I religiously back up my systems, etc. and if my current system crashed I can afford to purchase a new system immediately and I'd be back up and running very quickly. If losing a computer means you can't post on Flyertalk for a few days, that is one thing. But if it would impact your ability to earn a living that is quite another thing. Only you know and can assess how big a deal being down for some period of time would impact you.

Now, I do keep a previous generation Windows laptop around for some unique, Windows only use cases now that I've switched over to a Mac for my primary computing. But again, that is only because there are a few weird corner cases that I need Windows for and a Mac simply won't work. But I'm not keeping it "just in case" as a spare.

But would I keep two equivalent Windows computers around "just in case?" No, I wouldn't, but only you can determine the right path for yourself.

Regards