Do the S950 and T4 have MIDI via USB? The P105 has a USB jack...

The thing about adding an 88 wooden action to your arranger is that you will find that yes, most synth and brass, organ, etc., sounds are easier to play from the lighter action. But you will gain far better dynamics control with the 88 for piano, Rhodes, etc., sounds.

There's a reason, after 400 years or more, we haven't standardized on ONE type of action for everything!