I rode my last derailler bike about 8 years I believe before the chain actually gave out. Admittedly not every day by any means.
I have to admit I just don't find myself with the energy to get into the debate again. I'm just saying, I own both derailler and IGH bikes, and I don't see any change in the maintenance. Even if the chain does last twice as long with an igh, I would still stick with a derailler for summer riding (including riding in the rain) as replacing the chain and cassette every 3 years would be worth it for me, and it would take a while to make up the cost difference in the long run. And technically either chain requires adding a little oil after riding in the rain a few times to keep it from squeaking.
I await the OP's reply about whether they're riding in regular snow and ice kind of stuff.