I think if we overdo it with Stitch-related hats, the original Stitch Hat wouldn't be that special anymore. A pin set would be fine, maybe even a shirt like a jersey that had the face of the character on the front and it's experiment number on the back. I would have to say no to more hats though, 3 (Stitch, Angel, Red Stitch helmet) is more than enough of them. Especially if they are as easily obtainable as they were in OVMK, but I don't think they will be.