I've owned 4 Skylines - 2 JO5s, a 55-01, a DJ4 and one USA 4-94. There is IME no comparison quality wise - don't get me wrong I love Skylines, they're workhorses, they sound and play great and they're perfect for the gigging bassist. The build quality is perceivably as good as the USA models but main difference as far as I can see is in the quality of the woods.
The 4-94 literally took you're breath away whenever you opened the case - it was a work of art. Mine had a beautiful quilted sunburst top (you could feel the quilt with your fingers), stunning bird's eye maple neck and gold hardware - I had to sell it because I was scared to use it. It was also a lot lighter than any Skyline I owned.
Are they worth the extra mahoney? I don't think so.