I want to add that these are the reasons I think 1♦ is terrible: 1) It doesn't preempt the opponents as much, who can easily be on for 4M when my hand is this concentrated in diamonds. It is not unusual to play 1N= after opening 1N when the opponents are making 4M. It is also very frequent that the opponents can outcompete us in one of the majors if we open 1♦. 2) I think it's way more likely 1N makes than 3♦ if we are going to play this in a partial, though 2M may not make as often as 3♦ if partner has a transfer and pass sort of hand, I am not sure. 3) I think partner will bid 3N too often over 1♦, 3♦, but I am open to being proven wrong about this. 4) This hand is not very good for slam purposes anyway and the number of hands we can actually get to 5♦ when it's right after I open 1♦ is very small, the diamonds are not truly solid and being balanced is a huge liability. I think it's easy to overestimate the number of good slams we miss by opening 1NT.