Finally got my Wills in. Super happy with the custom measurements. Went with an XL (normally I buy American stuff in a large), and got some length taken off the sleeves and center back as I have dumb proportions. I still think the sleeves are just slightly too long but that should get just about perfect once the sleeves start stacking.
Love every bit of this jacket with a couple exceptions: the two-way zip is a little finnicky (you really have to grip both zipper pulls tight together and make sure the zipper is seated firmly before you can zip it up), and the lining is very nice but kind of highlights that somewhat gross waxy feeling at the unlined cuffs. Really just minor things and I won't care after a while.
I was worried about it being too heavy to be practical, or too non-breathable, but while stiff it's not all that heavy and is quite easy to wear. It's not exactly breathable, but does a good job keeping rain and wind out (already tested). Also, because it's so stiff, it doesn't drape close to the skin but rather sits in the shape it wants, which kind of allows for more airflow between the jacket and the skin than you'd expect (e.g., in the sleeves). Can't wait for this thing to break in.
Unzipped:
Gratuitous "it stands up on its own!" shot: