3♣ = min
3♦ = non-min, no shortage (unless stiff honour)
3♥/♠/N = non-min, shortage in ♣s/♦s/other major
After 3♣, 3N is natural, otherwise it's frivolous. Also after 3♣, responder has the option to bid 3D as a shortage ask (with equivalent responses). Atm, anything else is a cuebid.
We're basically using this system as a default after someone suggested it to me in one partnership and I liked it enough to introduce it to others, but I'm wondering if there's anything of equivalent or lesser complexity that people would recommend over it (none of my partners would agree to anything more complex). Or, if people think it's a decent system, I have a couple of questions for people with more experience of it, in particular of the inv+ version (the only way we could have it as GF+ is if we have 3M as a limit raise, but I think it's marginally better preemptive):
- After opener's 3♦, would it be better to have responder show shortage analogously to above? (atm we have normal splinters at the 4-level, but otherwise he could be more or less any shape consistent with 4+ card support). It would occasionally cost us the Frivolous 3N, as above, but then, so do the responses above. That said, opener seems to be captaining the auction at that stage, which feels awkward.
- Once we're GFed, we're often left with 3M as a free bid. I haven't put much thought into what better use we could make of it. Any suggestions? It would need to be relatively intuitive again, or my Ps would never remember it. One option I've thought of is effectively Frivolous, allowing 3N to become natural. Another is allowing P to bid 3N just to deny shortage. Neither of these make much sense if P's just bid 3♥ to show ♣ shortage, though... The last is some kind of keycard ask/tell.