John David Stone writes:
There is one significant difference [between R6RS and R7RS-small libraries], however: versions. Under R6RS, I have the option of teaching students how versioning of libraries works; under the proposed R7RS, there would be no language support for that topic.
The WG decided by unanimous consent to take no action on this ticket.
The WG's view is that the R6RS library versioning system was insufficiently tested against implementations when it was proposed, and hasn't received much attention since. It is the view of at least some members (Alex Shinn and John Cowan, notably) that versioning is better supported as an application standard outside the language: see Snow for a proposal along these lines.