As for the warranty, I always buy with my credit card with extended warranty, so I get two years, one year from Apple, and one year from the credit card. I use Amex, since they will cover Apple refurbs. OTOH, if you get a "refurb" from some third party seller with a non-Apple warranty, Amex won't extend the warranty (which seems reasonable).
Ah, if I did get the Pro, I would get it new from Amazon or Best Buy since it's on sale right now. I think if the sale didn't exist (which puts it at the iPad Air's price) I would likely just get the Air. I don't use my iPad a ton but I do lots of streaming on it, and also....
I am upgrading from (drumroll) the 3rd Gen iPad (The New iPad, as it was originally called). So yeah, my unit is quite old, and it has iOS 8 (?) I think, but it still works well considering. So, anything I get will be a massive upgrade anyway. Tbh, I hadn't even considered the Pro until I realized the Air didn't have ProMotion and had 1 gig less of RAM, and also that it was on sale from a couple retailers.
My only nagging hesitation was the white spot. It definitely doesn't plague everyone, but there's tons of threads of people saying the spot appeared over time.