The most popular weak Notrump range was 10-12 (almost 1 in 3 chose it). A BBO forum found 10-12 was by far the biggest winner individually as far as positive imp expectation.
Kit Woolsey said
“The main advantage of light opening bids is simply that opponents don't bid as accurately when you open as they do when they open. Whether this gain is worth whatever losses exist from light openings is something each partnership has to judge.”
“I'm a big believer in the merits of opening balanced 11s. It frees you from ever having to inflict the abomination of pass-pass-1♦-pass-2NT on your partner… [but] It does strain 2/1. A lot.”
But a number of comments revealed there was not a lot of joy about its effectiveness:
“I have one partner with whom I play 10-12 in a Precision framework. He is wildly enthusiastic about this bid, while I am less so, by far…. there is one often overlooked disadvantage. When you don't open and the opponents declare, the negative inference that you do not hold 10-12 balanced can be quite helpful to them “
The “major critique of super-weak NT openings is that they wrongside many contacts.”
“I think 10-12 … would be fine. I played this with one partner on and off for 2 years and got little benefit from the opening bid itself.”
“Having played 10 - 12 when the vulnerability is right with one partner for quite a while now, I can't seriously recall the last time it really gains.”
So there are pros and cons to opening a light 10 or 11 hcp 1NT: pre-emption versus wrong siding and missing certain part score swings. The occasional telephone number was discounted as fairly rare but it is a real factor that makes a big difference in certain events.
I can only conclude that while opening 1NT 10-12 or 11-13 feels real good it is not a major systemic loss if in our system we have to open 1NT 12-14 or higher. The 12+ weak NT can still act as a dumpster bid for parking our garbage hands and thereby make other openings more effective.
The big question still remains: Does opening 1♦ (or 1♣) light with a balanced 11 hcp really help us? I keep finding the higher rated players seem especially aggressive. Could it be true that our light openings only help keep our opponents out of trouble? That’s the very thing I discovered playing against sleepy little old men and wily little old ladies. But is it quite different in regional contests or for that matter against world-class competition?
The poll question is: Assuming our system can handle it, does it help or hurt to open 1♦ with a balanced 11 high card points?
Plus... it's free!