I think this feature could include two additional or exclusive sub features.

Merge mediums / tracklists (+recordings)
Let's say we have an original release with multiple re-releases that didn't get the same tracklist for one reason or another (see related ticket MBS-318 for an example).
We would like to merge those two mediums (this will also merge recordings).
This could be achieved by exposing what already exists now to user interface.

Merge recordings (only) of the selected tracklists / mediums (while not doing any tracklist / medium merge)
Now let's say we have an original release with its associated pseudo-release(s).
Track titles differ while they should be pointing to the same recordings.
Very frequently, that's not the case (see related ticket MBS-2425 for an example).
We would like to merge those two recording lists (merging each recordings one by one in the appropriate direction).
As the order matching is already done it would be less painful than doing this manually.
In this module or merge strategy, allow different track count so as to allow merging of those frequent japanese editions with bonus tracks first tracks' recordings with regular editions all recordings.