The above link would suggest you are incorrect, you can set a "DefaultServiceVersion" in the Blob Service Properties using the management API.
I prefer to avoid implementation-specific headers as much as possible, especially in a case like this where I'm using the Range header in a way that's defined in the HTTP 1.1 protocol spec:
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
I'm writing a client library to manage progressive download of content--it may be hosted by Azure or somewhere else. I expect every server to properly implement the HTTP protocol and I don't want to shoehorn implementation hacks just to get Azure to behave
properly.
Ryan