Not trying to start anything at all here. My curiosity has hold of me and I always wonder (after having done it myself) why at times breeders reach back to significantly older genetics. What is it in these two are you after? Did they work especially well for you previously? Just curious is all. Never used 335F directly, long story why, blame goes to the can store not the bull. Never used 52F either as at the same time owned a robinson son that worked well for us.