They should work alright. I'd leave the seeds in the pods and the pods on the plants to let them receive all the nutrients possible. If you must cut the plants before they dry down, then hang them to dry. Shell out the seed when the pods are dry.

George

For best results they need to dry on the plant. There are instructions at the link. Scroll down to 'Broad beans' (ie favas).

Here is a link that might be useful: Saving fava seed