I've swapped seats with my husband on 2 different flights to Hawaii without any problems.

The Policy & Procedures manual specifically says that it is allowed as long as it does not disrupt the "integrity" of the BF or F cabin. I don't believe there was a mention of how often you can swap.

As I said, we didn't have any problems and on our last flight, the BF attendant, upon hearing I was in cattle, brought me back a sundae

I would advise the F or BF attendant of your plans when boarding. If they give you a hard time, tell them to read the Policy manual