The spec says that the command supports it, not that the driver needs to wrap it. I had already added comment to DRIVERS-98 for this: https://jira.mongodb.org/browse/DRIVERS-98?focusedCommentId=420774&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-420774

First of all, this makes the implementation a lot easier for us. Each subsequent fetch listens to the already existing ``batchSize()`` method, which already allows you to change the batchSize for each subsequent getMore. Our docs at http://uk3.php.net/mongocursor.batchsize say "The batch size can be changed even after a cursor is iterated, in which case the setting will apply on the next batch retrieval. " and I see no reason why command cursors should behave differently than normal cursors.