The problem I have is in determining what the actual definition of: fully weighted (piano hammer action), weighted, semi weighted, and synth action is.

Some people refer to weighted as what the Ketron SD1 and Yamaha 9000pro keys are, while others refer this to only mean fully weighted 'piano hammer action' keys which Fatar claims to have patented: http://www.arbitermt.co.uk/studiologic/hammer.htm

I personally expect a keyboard which 'claims' to have weighted keys to have at least the weight & feel as the keys on a Yamaha Clavinova or Technics Ensemble Digital Piano.

I classify the key feel of the Ketron SD1 and Yamaha 9000pro as 'semi-weighted', and the keys of ALL currently produced 61 note arranger keyboards as merely synth-action.

George, that being said, I expect an 88 note arranger keyboard to have fully weighted keys similar to the Yamaha Clavinova/Technics Digital Ensemble Pianos, and that 76 note arrangers have (to keep it more portable) semi-weighted keys similar to that of the Ketron SD1.

I also prefer the shape & size of the keys to match the size of standard piano keys.

Scott