I know this was brought up before but was there ever a final answer?
It is now November 2017 so the other thread is quite old
What does Revolut use to transfer money from our Revolut accounts to US banks?
SWIFT or ACH ?
Revolut support told me SWIFT but my US bank has not charged me the incoming SWIFT fee the past two times I used Revolut to transfer. It is a little like Russian Roulette, so I am going back to Transferwise to be safe. Much rather stick with Revolut though!