Behavior of the plugin with "iw" motion with a count

[Aster89]

Given this text

Vim 7 is recommended for full functionality.

and the cursor in the middle of the word recommended, if I press v4iw, what gets visually selected is the text recommended for , including the trailing space, which is in line with :h iw (indeed, it reads White space between words is counted too); at this point, if press S), the text becomes correcly

Vim 7 is (recommended for )full functionality.

On the other hand, if I start from the same initial conditions and press leaderys4iw), I obtain:

Vim 7 is (recommended for) full functionality.

I expectated that the two command sequences should lead to the same result.

Is my expectation correct and there's a bug? If not, what is the explanation of the current behavior?