Either option.... warranty is good because it saves space and also can help with file retrieval and whatnot if there is a catastrophic failure. But spares... always nice!!! Pain to store, but can be switched out in a matter of minutes.
As for Macs... I know they are getting more and more compatible as the years go by, but when it comes to software that is more proprietary or isn't a popular home program, compatibility is a risk. I would stick with systems you know.
And thanks for the welcome, tomato!