Applying the Martin Defense to Interference over a weak NT

I recently became convinced to play the Martin Defense to interference over a weak NT.  I've always been a fan of negative doubles after a 1NT opener (of any range except 10-12 when I think penalty is probably more prudent).  But in the Martin defense, double shows exactly two cards in the suit bid by the interferer (regardless of the meaning of the bid).  It also shows sufficient cards to be reasonably sure they're going down, a good 9 to a good 12.  Anything more and we should probably try for game and anything less and it's better not to double them.  Given the generally balanced nature of the hand (opener has a balanced hand and if we have a reasonably balanced hand), then it's reasonable to assume that the entire hand is balanced -- not guaranteed of course.  Thus the number of total tricks is likely in the 15-16 range rather than anything more.

The first time we played it, it didn't come up and tonight it looked like it wouldn't again until the last round.  I opened board 1 with 1NT (12-14) as North (none vulnerable obviously) holding ♠A97 ♥76 ♦AKJT ♣JT53.  LHO bid 2♠ and partner doubled, showing precisely two spades.  RHO bid 3♠.  Well, this was an easy one.  They were contracting for 9 tricks on an eight card fit, while we have the balance of the high card points.  I doubled therefore, hoping for 100 our way (better than making 1NT) or even 300 if we were lucky.  Before the opening lead, we were told that 2♠ actually showed spades and a minor (Cappelletti/Hamilton), but it wouldn't have made any difference to our methods.  Partner led ♣4 and dummy came down with ♠J52 ♥KQ942 ♦53 ♣982, a reasonably good dummy from our point of view in that probably the hearts wouldn't be worth very much being most probably opposite shortness and with dummy being short of entries.  Partner came up with KT of trumps and we managed to get the contract down 3 (+500) for a top.  The best we could do unaided was 120 with our 23 hcp.  As predicted, the number of total tricks on the deal was on the low side: 15 (9 our way in diamonds and 6 their way in spades).

I guess you can count me a convert!