I did measure water capacity... but I'll wait until the new batch of brass ships before I would provide data. I talked to my contact there today, and looks like first part of the year they'll have some rolling off. If I remember, I'll come make an announcement thread here after that happens.
This next batch will be a production run, while the earlier batch was just a little blurp. The full production brass is likely to be different than the first batch. So, I'd wait to get a hold of that before you go making detailed decisions. When I get some, I'll happily send you a couple pieces for eval if you like.
Regarding dies, I send 3pcs of fired brass to whidden to get custom FL sizers /micrometer seaters made. You can get your first rounds loaded with 6CM or 6.5CM sets easy enough.