My observations of pellet training RES can be found here:
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=508098#Post508098

I rarely see a RES rise for a floating pellet. It happens every now and then, but not often.

I've not seen any of my YP come to the top for pellets.

I think you're onto something with this line of thinking.