Must Haves:
1) GCC Legal
2) Strong 1♣
3) Weak NT
4) Unbalanced 1♦
Highly Desirable:
1) 5-card majors
2) 2♥/2♠ = weak 2
3) lean toward natural bidding
4) flexible enough to go strong NT (14-16 or 15-17) in 3rd/4th seat (assuming relaxing requirement for 5cM and/or unbalanced 1♦)
Wiggle Room:
1) Ok for slightly off shape 1NT (for ex 5-4-2-2)
2) Ok for 2♣ to show 5 club / 4 diamond hands, if needed (but of course, would rather promise 6)
3) 2♦ can be whatever it takes to make the system work
Approach:
I'm looking at this as trying to improve 2/1 and Polish Club and not trying to compare to Precision or any other strong/multi club system. As such, I'm not really interested in working in ultra aggressive opening 1 bids and I'm perfectly fine with 11-17 1M openings. When there's a choice, I'd like to have any system weaknesses (hopefully few) tucked into the same places you'd find them in 2/1. If there's an existing system that meets the criteria, I'll gladly look at that. I've already drawn some inspiration from Miles' "Unbalanced Diamond" (UD) and Varvel's An Unassuming Club (AUC).
Here's my 1st try:
Opening Bids
1♣ = balanced 15-17 OR 15-17 5+ clubs (no 5cM) (also 4=4=1=4) OR 18+ any distribution
1♦ = 11-14 artificial, unbalanced hand (no 5cM) OR 15-17 4+ diamonds, unbalanced (no 5cM)
1M = 11-17 5+ M
1NT = 12-14 balanced
2♣ = 10-14 6+ clubs
2♦ = whatever
2♥/2♠ = weak 2
Responses to 1♣ (redone based on feedback)
1♦ = 7+, 4+ hearts (6 & 5+ hearts ok)
1♥ = similar to above w/ spades
1♠ = art. neg., 0-6 OR 10-12 bal GF
1NT = 7-9 bal no 4cM
2♣ = 7+ 5(6)+ diamonds (no 4cM)
2♦ = similar to above with clubs
2NT = 13-14 balanced
Also considering an approach very similar to SPRY:
1♦ = 5-9 waiting
1♥ = 10+ unbalanced, artificial, GF
1♠ = 0-4 (no A), artificial, bust
1NT = 10-12 OR 15+ balanced GF
Rebids After 1♣-1♦/1♥(Walsh Relay)
1M (accept Xfer) = 3+ M, 18+ GF
... [Responder bids 2M as a general purpose confirmation of 8+ card fit; other bids tend to indicate only 4]
1♠/1♦ = usually exactly 4 spades and a canape bid, 15+
1NT = 15-17 Balanced (not 4 M)
2♣ = natural 5+, either 15-17 w/ exactly 3 M or 18+ w/ 0-2 M
... [Responder can bid 2♦ to ask:
2M (super-accept Xfer) = 4 M, 15-17 (either bal or w/ clubs)
3♣ = natural 6+, 15-17, 0-2 M
Other bids = natural, 0-2 M, 18+ GF
Hopefully, that gives a good idea where I'm heading.
Questions to ponder:
1) Any glaring errors so far?
2) It seems this forum tends to see a natural 1♦ as a net big plus. Is the artificial unbalanced 1♦, which clears up tremendously after a rebid, still too vague to be useful?
3) Any tips on improving responses and rebids after 1♣ opener