The porter escape, mounted either singularly or in pairs towards the centre of the escape board is a popular escape. Each escape has two exits past "feelers" that prevent re-entry but offer a good wide exit to the departing bee. It is mounted over a surprisingly generous hole, so there is good pheromone transmission attracting the bee to the escape. The porter escape also has a removable "cap" to easily inspect it to make sure the exits are clear.
This is used extensively by commercial beekeepers, mostly in the "pairs" arrangement and they keep coming back for more, so you know it works.
Note that there needs to be plenty of room below the escape board for the exiting bees to easily leave the honey supers. Severe congestion near the escape exits make clearing the honey supers problematical. So if not using a deep 50mm escape board, a spacer rim needs to be added below the honey supers and the escape board.