i saw this tested thoroughly a while back using an older version of jquery, maybe the updates of the new version made them closer together in terms of performance. I haven't been able to recreate results where there was a significant difference in performance.
In either case this wasn't a question of performance, it was a suggestion of added functionality to existing methods, sorry i threw it off topic.
I can't think of a single reason not to have it, if performance was an issue it wouldn't have been implemented on the init method.
-- Kevin