Picked up a Sinn U1 DS just this week.
The dial reminds me of Grand Seiko in a form or another.
How's the thickness and weight on the 556? I often wear a Tudor BB41 as my 'everyday' watch, but it's a big, hefty thing. I've been starting to eye a 556 B as an alternative, and am curious to hear how others feel about their 556's.