You are correct, your way is better if 3♦ shows 4-3 or 3-4 in the majors (I did not read carefully enough what you wrote, and not even what i wrote myself !) :) But in the sequence: 1nt-2nt 3♣-3♦ ? I dont see why opener cannot bid 3♥ with 5 card hearts sometimes (Especially if he is not afraid of a lead directing double of 3 ♠, and he prefer to declare the hand himself). If responder shows 4 hearts, opener can play play 4hearts without showing that he has 5 hearts: 1nt-2nt; 3♣-3♦ 3♥-3♠ 4♥ If responder bid 3nt, opener can still correct to 4♥. And I assume that opener can jump directly to 4♥/♠ over 3♦, if he think that he should declare :) Another (stupid) idea that is that opener shows that he might or might not have one major: 1nt-2nt ? 3♣=Denies 4 or 5 card spades.(Opener might or might not have 4 or 5 card hearts). 3♦=Denies 4 or 5 card hearts.(Opener might or might not have 4 or 5 card spades). With both majors one possibility is that opener bids 3nt directly (Leaking information if responder only was interested in 5 card majors). This leaves room for responder to choose who should declare. After 3♣ from opener, responder bid 3nt if he is not interested in hearts, or bids 3♥ with 3 card hearts, and 3♠ with 4 hearts. Simillary after 3♦ from opener responder bids 3nt with no interest in spades, and 3♥ with 4 spades and 3♠ with 3 card spades.