Zelandakh, on 2013-July-16, 01:42, said:
What is the advantage over 2♦ showing the bad hand and 2♣ (and all other rebids) being constructive?
Try thinking the possible auctions through yourself.
For instance. A 2
♦-rebid showing a sound overcall with 6+
♦ (too strong for an immediate 2
♦) is a much nicer bid than a nondescript strength-showing 2
♣ cuebid. Same goes for 1N and 2
♠.
On the other hand the bad overcall will usually be 5 cards (since no 2
♦ bid), so partner should be in a good position to choose a sign-off spot at the 2-level. But the advantages lie with the constructive bids.
It's lebensohl-ish and pretty clever imo. It could be applied anytime the cuebid is cheaper than rebidding the suit.
The treatment is devised for forcing advances, since with nonforcing advances one could just pass many of those hands that should otherwise bid 2
♣.