-Managing multiple registries at multiple stores is a pain. Automatic sync helps alleviate that headache.
-We allow people to add any item on the web or with a barcode. Now you can register for a random item at a random store without having to set up a whole registry there (if they even offer the option).
-We do price comparisons on each product. Other players just aggregate your registries, but don't detect that you might have the same exact mixer at Target and Bed Bath & Beyond. This way, we can show guests where the mixer is the cheapest -- you don't care where it comes from.
As far as making money, we use affiliate links for any product at stores with affiliate programs. Fortunately, Amazon tends to be cheapest for most products and has a good affiliate program.
Thanks again for the feedback.