My motoros, humerosa, and hystrix all eat New Life Spectrum sinking pellets. At first, I soaked the pellets in blackworm juice or fed shrimp along with the pellets. I'm a firm believer in the complete nutrition of the product. However, they graze on them slowly over a period of hours rather than aggressively inhale like they do with live worms or frozen food.
I would love to get my fish eating pellets as a staple diet as NLS is healthy, clean, convenient, and relatively cheap. At this point, I'm just not willing to risk my collection which has taken me a long time and a lot of money to acquire. I want my rays to grow fast and grow big, so I'll stick with the proven technique for now.