TheParadiseTrio,

Some answers for you:-

1. Is anyone can tell me if a XD-3 will read the registrations of a X1 without any changes ?
>>>AJ: No. You will need to make changes since both units are not identical (different buttons, LEDs, functions...etc)which are some of the data stored by Registrations.

2. Will the midifiles sound Exactly the same ?
>>>AJ: No. They will sound better due to better sampling techniques used in the XD-series.

3. Will the XD-3 read a 88 notes keyboard ?
>>>AJ: Yes.