> 4 writes out of what, 3000?

Depends on your device capacity and how much is in actual use. Wear leveling things also wear things while it moves things around.

> For something you'll need to do once or twice ever?

I don't know you, but my cloud storage is living, and even if it's not living, if the software can't smartly ignore files, it'll pull everything in, compare and pass without uploading, causing churns in every backup cycle.

> Isn't that usually symmetrical? Is yours not?

GPON (Gigabit PON) is asymmetric. Theoretical limits is 2.4Gbps down, 1.2Gbps up. I have 1000Mbit/75Mbit at home.

> I don't know you, but my cloud storage is living

But you're probably changing less than 1% each day. And new changes are likely already in the cache, no need to download them.

> if the software can't smartly ignore files, it'll

Backblaze checks the modification date.

> GPON (Gigabit PON) is asymmetric. Theoretical limits is 2.4Gbps down, 1.2Gbps up. I have 1000Mbit/75Mbit at home.

2:1 is fine. If you're getting worse than 10:1 then that does sound like your ISP failed you?