mgoetze, on 2016-January-29, 15:11, said:
The reason is surely that you live in ACBL country, where all the other bits needed to actually make such a system good (transfer openings, artificial INV+ relays, etc.) are proscribed.
(Actually I haven't come across such a system in Germany either, even though it would be allowed here. But I'm sure it can be workable.)
When I encountered it, their set of agreements definitely needed work. I'll take your word for it that this can be done. For all I know, a system where a spade overcall shows 2 to 4 spades can be made to work, although it is hard to see just how.
As I recall with my encounter: Rho opened 1S, I overcalled 2C, and they were not clear on whether, after my overcall, 2H was still non-forcing. One thought it was, the other thought it wasn't. Sort of a reverse negative free bid agreement. If I pass over 1S, their 2H is non-forcing. If I overcall, their 2H is forcing, or so one of them thought.
I have played against unusual systems that seem to have merit. This, as they played it, wasn't one of them. I never saw them again.
But still, it wasn't like the 6D bid. That was not any sort of system, however ill-advised.