I think a good system would be to be able to put 8 items of your choice in the vault to be able to keep. This equates to one item per weapon slot and armor slot. (Unless I miscounted) Or you can have more weapons less armor, you get the idea. This way a limited amount of items are taken to the main game so beta players feel rewarded but first time players aren't going to feel left out for having guys running around with a bunch different legendary guns stomping kids. But levels should be reset. Leveling was accelerated in the beta so you would have time to max all the characters. And all the players that want to be all "I WORKED HARD FOR ALL MY STUFF AND PLAYED FOR 17 HOURS AND ARAFAJRGAGHAGSKGAJSVG" will be level 8+ again in like 6 hours anyways.