In light of the bylaw effort, here is some information to help us decide on RB's role. This information is current as of this writing, but the bylaws have not yet been approved.
Code changes will be approved by lazy approval, meaning automatically after one day except if there is a veto. In case of a veto, consensus approval is required (+3 binding votes, no -1).
There is no requirement for RtC. No specifics on RtC vs. CtR are in the bylaws, but decisions on that are deferred to a separate document.
So, I see two roles for RB:
1. As a way to provide an optional review before committing, as Christopher suggests. This would not absolutely require any ship-its because we start with lazy approval.
2. As a way to provide a review for consensus approval after a code change veto. As Christopher points out, we may need to post a "[VOTE]" to dev.
A contributor could use other means for the above, like pointing to patches posted to Jira, but RB is there and may be convenient.