Remember with marines you are a MARINE (sorry phrog) first. If that's more enticing to you than being a naval officer and pilot then go for it. I had a really hard time deciding between the two, but in the end I went with navy (making me third generation navy). Marines have got a lot of great stuff to fly, pay is the same, but the general mindset and way of thinking is different in the corps. You'll have to decide which is better for you and yours.
As far as I understand it, you are under no obligation until the completion of OCS. Your OR will know for sure. Best of luck to you.