I imagine that the unsigned location would be put in SignatureProperties. I don't like this. I'm happy to leave that to the application. My strong objection is to the Transforms within SignedInfo being viewed as hints. In other words, I feel that we could allow Transforms outside of SignedInfo as long as the unsigned transforms were applied, and then ALL of the signed transforms were applied.
Applications can decide what unsigned transforms they wish to trust.
You characterize one of them being that Location and Transforms are only a hint. So, I agree with you that Transforms should always be done but disagree about Location. All of your other issues seem, to me, to be only relevant to Transforms as hints. Aside from our agreement over Transforms not being a hint, my comments were actually mostly about my expectation that Location should indicate where the object is rather than be a hint about where the object is. As you can tell from the bottom of my letter, I cannot tell at this point whether Transforms will be handled by core code or also serve as hints.