The 249 is my first PAM. I picked it because of its unique dial, and its stealth. I wears smaller than its 47mm size. It works with everything from ammo to gator, and you can wear it with a suit.
Its historic, it has a reliable movement that's relatively easy to service.
Don't get me wrong. The 587 is beautiful, and it says Marina Militare. But if I had to get rid of one over the other, it would be no contest.
Whatever you choose, you're not wrong!