About to buy a 2nd Hand MBP – Only InfotechRisks?

After lurking on this subreddit for a while Ive often seen "macbook pros" can last for 10 years – I own a 2017 MBP and a 2014 iMac 5k and neither have had any issue. Im attracted to an older MBP because a) if something goes wrong or my 2017 MBP gets stolen, I have a backup and b) I like the idea of having a personal MBP to segregate business from personal (the MBP is used primarliy for business, Im a consultant)

The question I have is, what risks could buying a second hand MBP have? battery life is one to mind, this one Im buying (listed here ) is marked as "after market battery" and the seller assures me it was installed by Apple and no problems with it, before I go up there tonight and hand him the cash, what would you be checking out to sooth any paranoia? I think I will be fine, just appreciate any educated opinions 🙂

Im not all over what models are better than others, Ive seen on this subreddit people saying "x model" or "x year" avoid because of the battery etc so thats partly the basis for asking, the other part is existential risks that could be flagged to avoid disappointment (and loss of money) 😉