Hi Graham,
I understand your thoughts that you think it is useless to buy a watch with a useless complication.
Just see it this way: There was a (maybe stupid) competition between several brands to create a dead second movement.
If Omega had one in their catalog Rolex also wanted to be able to show/sell one and vice versa...
Concerning the decision to buy one or not - I can only talk for my decision, and maybe other collectors think a similar way - is the rarity of the watch for a thematic collection.
I collect mainly Omegas and as a special subject chronometers, so the decision was clear for me...
Have you had a look on the desk clocks with the 8 days movement - also dead second chronometer grade movement which I included in my post?
They are very reliable and accurat, no issues at all - similar dead second construction... but as the movement is about 59mm in diameter it was much easier to build a reliable movement. And they look marvellous on the desk
regards
Erich