You really have to look for edge cases to get a notable impact on performance. An example: if you would do an index lookup on the combination of edge label and property key when an edge label was reused once, execution time would scale as log(2N) = log(N) + log(2). I consider this an edge case because starting a traversal on a relation is often considered an anti-pattern.
Personally, I like reuse of edge labels, but only if the semantics of the relation is exactly the same. Compare with the semantic web ontology language OWL, where you can define a domain and range for each relation. There, domain and range can consist of multiple vertex types.