[Winstonm]

It makes sense to me that if I was intending to jump over a simple rebid to show a limit raise that the same jump after a jump rebid would do the same thing, i.e.,
1S-1N-3C-4S should show the limit raise. If my partner has a game force hand and I have a limit raise I doubt we will be stopping at 4S so the bid IMO is best used to simplify the auction and define responder's hand.

Also notice that in this case by bidding 4S as a limit raise captaincy is transferred as it should be, when one of the hands can be closely defined in terms of strength.

[1eyedjack]

4D shows club support in my book.
Responder does not have much in Spades, in my view, given the 1N response.
Responder could have Club support and still bid 3S previous round.
And now he cannot conceal excitement in Clubs given the 4C bid.
Anyway, just my opinion.