I had had around 300 BN Resource Credits delegated to my alt account @revise.spk which runs my spk node and follows my main accounts voting trail, and that had been enough I think post HF26 to cover the operational costs, but I noticed a couple of days ago that my RCs were steadily getting drained...
So I upped my delegation to 500 BN and now everything seems OK - steadily getting back up to 100%
It's a bit difficult to tell if this just RC costs getting more expensive as I've got a PD on the alt so that would have had an effect, but I don't think too significant.
I'm hoping the 500 BN RCs is enough to cover the account after the entire PD.
It only takes a check once a fortnight at least!