We exported around 3.5 kWh in the session today, but only because we had a full battery going into the evening so had spare power without importing. Personally, I don't think "opting out" will do anything to the pricing. They've been quite happy to reject every single bid in some saving sessions so far so they're quite happy for DFS to not actually save anything if they have other sources they can call on. It's only been when margin is tight that we've seen the better pricing.
I don't really think Octopus are managing their bidding properly either. In the two sessions Octopus ran prior to today, they saved ~109 MWh in session one (60 p/kWh offers to customers), and ~129 MWh in session two (72 p/kWh offered). So today where they bid 29.9p and offered 24 p/kWh to customers, how much did Octopus promise NESO they'd save? 271 MWh.
I'm not sure I get the logic that warrants promising a 271 MWh saving when the previous sessions at ~3x the price saved less than half that, but that's what they bid. This is relevant because if they deliver <50% of the promised saving they take a penalty, so Octopus won't even be paid the 29.9p/kWh for today anyway. I guess they'll still pay what was promised to us, but why promise such a high saving that they won't deliver?