I'm pretty much in the same boat. The only thing I'm moving over are books, clothes, personal items, and cds/dvds. I have no idea how much it is exactly atm, but it's all in a space less than 5ft x 5ft, so I can't imagine it being very much. I'm debating on shipping vs. extra luggage. Both ways have the risk of things being lost, but at $100+ per extra piece of luggage, who knows. However, I have a six piece luggage set that I am bringing with me anyway, so I may as well use up the space that I have. It may end up being the same in the end.
The other thing is though, making sure what can/can't go through customs at the airport. That's always a hassle. The only thing I have that truly MUST be shipped (aside from books--I don't want to lug those around and pay overweight luggage fees) is my Sailor Moon collection (I'm a nerd, haha). There are figurines, action figures, and general collection memorabila that would not hold up in luggage and wouldn't even fit if I had a 20 piece set of luggage, haha.