I find the load times on the One X fine - on my One they were a pain
Subnautica is painfully long, thankfully it's only really bad on the inital load.
You can't really compare 6tf from last gen to 4tf next gen.
Its already been confirmed that the series S will do everything the series X can, just at a lower resolution
I agree, it gives an indication of performance though, and like I said I'm more bothered about other benefits over resolution.