It's really personal choice, do you like the 88, you've had it a week so should have a clue if it's the Panerai for you, if it's not and you really do love the 312 then i guess you'll go for it.
You can get a few opinions from here, but in reality it's down to you and you alone, you have the 88, you'll see and feel the 312 and you'll make the right decision based on your needs and wants
