Congratulations on your new E-Lop! I hope he does real well for you. How old?
If you trust the breeder and are impressed with the rabbits they have, I'd follow their suggestions and keep the rabbit on their choice of feed, as long as you can get it. There is nothing wrong with the Nutrena feeds. It is highly rated by lots of show breeders. And if the breeder thinks they thrive on it and it keeps their rabbits in good health and condition, it's a good place to start.
As the rabbit matures, it's needs may change. Based on Breeding and show schedules, you may want to supplement or change feeds. But give him a chance to settle in to his new home before you make any changes.