The premise that I was prepared to bid NMF doesn't compute. The double doesn't interfere with my intent to bid 4S, and I will have extra information during the play.
If I had a hand where I wanted the information I could obtain from the NMF, the double doesn't prevent me from doing so.
A redouble would suggest I don't want to know if partner has 3-card support, but rather whether partner would like to cooperate in punishing the opponents (invite strength). All partner needs to double the runout would be 3 cards in the suit.
A general principle would be that a call which takes up no room should not prevent you from doing what you wanted to do; and you should use it to advantage when possible.
Another case would be when it goes:
1S-1N (dbl), where 1NT was forcing and you would have had to rebid a 3-card minor perforce. The double took up no room, so you can still rebid a suit you actually have; but you can gain by passing with a 5-3-3-2 minimum and redoubling with a 5-3-3-2 mountain which would have normally rebid 2NT.
This post has been edited by aguahombre: 2011-November-13, 19:10