5/ Result two, what it costs sUSDe holders.
On the 93 active days where sUSDe was paying more than sUSDS, it still paid more than sUSDS after the buyback on 82 of them.
On the other 11 it slipped just behind, all of them within a tenth of the benchmark. Small and worth understanding why it happens.
Here is why it happens at all. The buyback takes its 10% whenever USDe is large enough. It never checks whether sUSDe can afford to give up 10%. Usually it can, because sUSDe pays well above sUSDS and losing a tenth still leaves it ahead. On the days sUSDe is only just ahead, the same 10% puts it behind.
For context, sUSDe already paid less than sUSDS on 243 of the 705 days we looked at, with no fee switch running at all. This is a market condition the design lives with and not the condition it creates.