Hi There - I am sorry, but I can't answer your question fully. No one has answered so I thought I'd share what I know. We use antifoaming molecules. We find that they all seem pretty similar in the applications we use. We've tried various techs including polysiloxanes and the like. Each time we looked at a new defoamer we have just ran a few trials with several different types and went with the ones that worked and which were then the lowest cost.
In short, I think it depends on what you have in your system as to which type of defoamer is best.
Sorry I can't give you anything more than you know already wrt your EO/PO chemistry. Maybe you will just have to run a few tests to see what works best, or maybe someone else who actually knows what they are talking about will comment.
Good luck anyway.
P