they say that it's best to stagger your racket holding arm after you toss the ball. i noticed that nadal has both arms moving in unison during his movement.
best example for this staggered service motion: pistol pete and steffi graf
I will pay closer attention to that
The thing is that with these movements that you develop at a very early age, and play with for so long, it takes a very long time to adapt to a new style. Especially if in the interim you lose matches etc while trying the new movement out. I guess he is not going to change anything remarkably.