Perfect. Thanks so much - I get the difference between post-hoc power calc and a CI. Tells you how people were targeting when they set up the trial, (admittedly based on p-hat) as it's what the FDA uses in setting sample size.

Only further tweak I've followed up on is that risk ratio, rather than difference in binomial parameters, seems to be reported more often. In the examples I ran, the difference between the calculations amounted to fractions of a death.