Hi Steve
The SOM NL 4300Z spool (to fit 4500Z) will fit and operate on the new 2010 4500/5000 series. There is a new SOM NL 2010 4500 spool (model no. 10ST5000F) that only works on the 2010 saltiga - while it appears to fit the 4500Z, the rotor hits the spool on the downwards stroke.
Also while the handles of each series are interchangeable, the new MC Works BB handle will only fit the new 2010 model. The machining on the MC Works handle is too thick to clear the side plate of the 4500Z series. There is a JM handle (no knob) that fits both series.
Hope this helps
Cheers
Les