I consulted with the developer who has done most of the graph database write operations for my department. He said the fewer operations you do against the database the faster the write process will go.
In the context of relationship properties vs relationship types, if you have all your attributes at initial write time then writing them as properties would be faster than writing each of them as a separate relationship type.
IE (in psudo code): Create relationship x with properties a, b, and c VS Create relationship a, create relationship b, create relationship c. The first would be a single write operation, the second would be 3 write operations.
However, if you have to merge each of the properties separately it would be a wash. IE (in psudo code) Create relationship x with property a, merge property b, merge property c VS create relationship a, create relationship b, create relationship c. Both versions are 3 write operations.
With that said, it seems the number of write operations needs to be optimized to the fewest possible while still resulting in the graph that lets you do what you need. The two following graph models will allow you to do different things, and which structure is best depends on your use case.
Hope that helps.