Vampyr, on 2015-January-30, 19:11, said:
I think the latter is interesting, and I have sometimes wondered about using Drury by an unpassed hand, but there are a lot of hand-types to untangle here. Plus you lose your 2♦ rebid (I assume) which seems like a high price. I would be interested in knowing if it can be made to work, though.
I've played a version of this in most of my serious 5 card major partnerships over the past couple of years, including Precision (which we added 2/1 just for this), Polish Club with 2/1, straight 2/1, and Standard American.
The basic idea is that you have 4 possible types of hands:
- Invitational raise of the major (typically rebids 4M over an acceptance or 2M over a rejection)
- Balanced FG (rebids NT; you can allow a 3NT rebid to show a minimum with a doubleton trump, or use the jump for something else)
- Balanced minimum FG with fit (rebids 2M over an acceptance or 4M over a rejection)
- FG with clubs (bids something else, including 3M with 5+ clubs and 3 card support)
Opener then rebids:
- 2D to say "accept game try with nothing special to say" and opener clarifies hand.
- 2H (after 1S opening) to show 5/4, nebulous about whether accepting game try. Inv raise now bids 2S or 4H (with double fit, you want to be in game). Bad balanced FG raise bids 4S.
- 2M rejects game try.
In the standard system, we reversed the 2M and 2D responses and didn't cater for the balanced min with fit (that went into a 3NT response, if I recall). That all worked fine, but I've never worked out whether there was a reason for reversing the bids.
Advantages:
- You can invite and stop at the 2 level. That's a potential 5-6 IMPs every time you do this.
- Responder can easily show strong balanced hands, which is a problem in many systems.
- Responder can show strong (say 16+) balanced hands with a fit with a sequence like 1H-2C, 2D-2NT, 3C-3H. Now you are off to slam in a sensible way.
- Opener can take over and start a slam sequence by bidding above 2M ("I'm interested in slam opposite an invitational raise"). Responder now cooperates in the slam try rather than trying to show their hand.
- You gain a jump to the 3 level, which is typically preemptive, without having to give up other 3-level jump shifts to something like Bergen.
Disadvantages:
- Opener can't bid 2D naturally. The hand often gets to bid 3D naturally (even over 2S), so the real issue is not being able to show shape with the 5/5 hands since the diamond rebid is actually what gets lost.
- It can be susceptible to preemption, but they still need a hand willing to get in the middle of a potentially FG auction.
- The opponents get to double 2C for something.
- You lose preemptive value with your 3 card limit raises.
Overall, in my experience it is a big win. It's increasingly common among Australian players, but I think the ideas came from Europe (Germany maybe?) initially.