[barmar]

In an auction like 1♠ 1N(forcing) 2♣ 2♦/♥, GIB plays that this only shows a 5-card suit, and that's what it frequently has. This can be a disaster if I have a singleton. I've seen it do this with 2 cards in the original major and/or 4 cards in opener's minor.

I think most human players play that responder needs a 6-card suit to bid it in this sequence.

[nigel_k]

I agree that a 6 card suit is standard but 2♥ constructive is quite useful, for example with xx AQxxx xxx Kxx, you don't really feel good bidding 2♠ after 1♠-1NT-2♣. I think GIB should learn Bart anyway because it's really far superior to being able to play some hands in 2♦. Of course you would still have the problem if opener rebids 2♦ and responder has hearts.

[barmar]

Do you think enough players know Bart that it would be appropriate for GIB to play it? I don't play it, and I don't think anyone I've ever partnered with has offered it when we were making out our CC.