I definitely don't think he wants to get a dropshot back, he prefers a deep return that will allow him to step back and attack with his cpen forehand. Look at his equipment, he even prefers the tenergy64 over the tenergy05 on his backhand, implying he is more comfortable mid distance than close, where he relies heavily on athleticism and his forehand/crossover footwork combination to complete the job.
I myself switched to RPB (left handed) after strugling with shakehand, and find it very, very natural to emulate his style. Lately, even I prefer deep serves to allow my opponent to attack it, so i can step back and send it right back to him.