I don't have information that will exactly help you out, but I want to help you get your answers.
I've listened to Athena F1, F2 and Polk RTi8 (more expensive than the Monitor 50) in the same setup, but not the Monitor 50s themselves. I liked the Polks more than the Athenas, which seemed a little less detailed. Keep in mind that I didn't do a comparison of the exact Polks you're looking at, and that I don't have a great ear.
I was a bit disappointed with Athena in general, since I had heard so many good things on this forum about them. Maybe the setup wasn't great...
Do you have a chance to go and listen to those three speakers? If so, you must do it.
I've listened to Athena F1, F2 and Polk RTi8 (more expensive than the Monitor 50) in the same setup, but not the Monitor 50s themselves. I liked the Polks more than the Athenas, which seemed a little less detailed. Keep in mind that I didn't do a comparison of the exact Polks you're looking at, and that I don't have a great ear.
I was a bit disappointed with Athena in general, since I had heard so many good things on this forum about them. Maybe the setup wasn't great...
Do you have a chance to go and listen to those three speakers? If so, you must do it.