Doesn't the upgrade break the warranty? I mean, you are going inside the machine which is sealed, isn't there a seal that says that breaking that will void warranty?
I'm not sure about this so asking.
I'm not sure about this so asking.
I'll answer your 2nd point first. The NVME drive is faster in transfer speeds, but thats not very noticeable in real world use unless you're transferring truely giant (100gb plus sized files). What really makes an SSD 'feel' faster in average use are the virtually instantaneous access times, which ALL ssd's have, even 'lowly' SATA ssd's.
Back to your first point, I've upgraded drives on several imacs, including twice on friends 2017 imacs, so for me, doing the upgrade is not a problem. iFixit rates the difficulty as 'moderate'. So even they dont think its that difficult.
Why not just attach an external drive? For one, to me that somewhat defeats the beauty of having an 'all-in-one', and again, since I dont find doing the upgrade hard at all, I figure why not just go internal.