I have two registries... One at BRU for sake of convenience and accessibility and another with Amazon for those who prefer online shopping... Plus, I have prime membership and would love the ease of using the completion discount and free shipping. The prices are more competitive on Amazon.
Neither registries are huge but I noticed that Amazon has more items on it than BRU. My friend said not to worry because Prime membership is widespread. I fully intend to buy whatever I need on my own but do want to make it more convenient if people choose to use the registry.