- 1C = hearts
- 1D = spades
- 1H = balanced 9-15
- 1S = strong
- 1NT/2C/2D = natural [I assume]
Now, I've written about system regulation before so I'm not going to go all through that again. But there's something interesting going on here: these transfer openings aren't all that hard to defend against (not compared to multi, say, or assumed-fit pre-empts, which are Level 3 and Level 2 respectively), so why is it that people react so strongly? Having played both Polish Club (a lot) and moscito (a little) I've seen for myself that people find the latter considerably more intimidating.
I suspect a big part of the reason is that in these systems all of the 1-level bids are affected. If you're playing 1D as a transfer to hearts, the chances are you're going to want new meanings for 1H and 1S as well. Perhaps none of the bids are particularly taxing for the opponents when you look at them individually, but having four unusual 1-level openings is four times as much for the opponents to think about. Certainly the intimidation factor seems to be closely correlated with the amount of unfamiliar stuff in the system, irrespective of how "difficult" it really is.
Here "amount of unfamiliarity" could mean either the number of things that opponents need to think about before starting to play, or the frequency that they actually come up. I would say the former is a better reason for restricting conventions, but the latter is important too - a call that comes up once in a session can be an interesting challenge, but if these things are appearing every other hand (or more if you're unlucky) it starts to become a little draining.
Another point is that, although there are many unfamiliar systems around, these transfer systems are unfamiliar in a particularly obvious, in-your-face kind of way. The unfamiliarity of systems like Polish Club is dimmed by all the nebulous minor-suit openings you come across. Transfer openings really look like something completely different.
None of these are necessarily very "rational" reasons for disliking a system, but of course that's not the point. If opponents feel a system detracts from their enjoyment of the game, it's not because they've done a detailed technical analysis. If a system appears to be difficult, then that's a problem.
Besides, not everyone is a bidding theorist. When I look at a 1D opening showing hearts, I can see straight away that I can defend against it exactly like a 1H opening, so long as I've managed to agree what my double and cue-bid mean (and it doesn't really matter which agreement you pick). It's really quite remarkable that that's all there is to it. But you do have to be thinking about it in the right way. If you're not used to looking for analogies like this it won't necessarily be so easy to grasp. I've seen enough people making the "wrong" cue-bid in this situation to know that not everyone is comfortable with this stuff.
I'm not going to lose sleep over whether transfer openings should continue to be permitted. But the fact is that many opponents do have a problem with them, and my experiences of this are enough to make me feel it was probably a mistake to allow these bids in general tournament play. It would be great if everyone could learn to love these things; but if a large majority of players do not want them to be allowed, as suggested on the EBU blog, then that cannot be easily dismissed.