Weak Notrump: 1C or 1D Opening?
If you had to open either 1C or 1D with all your weak notrumps, which one should it be?
Opening 1C gives plenty of room to unwind, play transfers where allowed, and investigate for 4-4 and 5-3 major fits below 1NT. However the 1C opening gives that same room to the opponents, where they can naturally bid all four suits, such as:
Double: takeout and/or value showing, and now 1D by advancer can be waiting/negative
1D/H/S, 2C: natural
2D: Both majors
Opening 1D with all your weak notrumps takes away bidding space for both our side and the opponents. Who wins?
The lack of bidding room means sometimes our side will end up in two of a major on a seven card fit (e.g. 1D-1M;-1NT-2M when opener has just 2 in M) - however that is only marginally bad as two of major can work better than 1NT on a whole set of hands. It removes the ability to play transfers, and has responder playing 1NT on the auction 1D-1NT, but a weak notrump hand doesn't have enough values to necessarily be the best one to be declarer of most contracts.
However the reduced bidding room really hurts the opponents, as they are unable to bid all suits naturally and have a bid of 2C or 2D for both majors. In addition, if they double 1D, advancer (partner of the doubler) has to bid 1NT, 2C or higher if no major.
Due to this competitive aspect, it is my opinion that opening 1D with all weak notrump hands is the better approach. In addition, I've come to believe that the big club split for balanced hands of 1NT 14-16 and 1D 11-13 is likely optimal in bidding design. When the Bread N' Butter series continues, let's see if that rings true.