Re: B.1 and B.2 results

>    + FFFE is already established in Unicode, so many multi-byte systems
>will have text-editors that can deal with the initial FFFE.

Right, but it's not necessary for the header. I can agree to using
this *after* the header has been stripped off...

>    + Generic text-editing tools will almost certainly turn the user's view
>of a US-ASCII header into garbage on multibyte systems, but would not turn
>ISO character codes <127 into garbage.

Well, given that ISO and US-ASCII share most of the same code points, it
seems that this is unlikely. As I noted, the only problem is for pure
16-bit encodings, which are reasonable scarce. 

>    + Many people will want to edit XML with generic text-editors on their
>systems in their native character codes.

Most of which use 8 bit multibyte encodings that are ASCII compatible.

I could be convinced that allowing 16bit header encodings makes sense,
as I don't feel *too* strongly about it. However, losing MIME
compatability seems a waste.