As you have eluted to we have not adopted the 2011 NEC still on 2008.
I may be to simplistic in my thinking and I have learned to give your experience and knowledge of the code a second or third look. I don?t take for granted what you say when you express your thoughts.
I would have thought after looking at 250.30 (A)(2) Supply-Side Bonding Jumper and 250.30(A)(3)Grounded Conductor would be coupled together in that 250.30(A)(2) would apply when no Grounded conductor is present, and 250.30(A) (3) would apply when a grounded conductor is present on SDS systems. Especially when you consider that the outside transformer must now be earthed and you must comply with 250.30(1) exception NO. 2 eliminating parallel paths for neutral current.
It seems to me the purpose for requiring the Supply side bonding jumper was in establishing a fault clearing path back to the source. The supply side bonding jumper would take away any guess work as to the fault clearing path for a system that is 480V verses a system that is 480/277V.
The fault clearing path between the 480V. system really couldn?t be called a neutral and calling it a grounded conductor was confusing. Calling it a supply side bonding jumper seems to take away the confusion that a path must be established back to the source.
Looking at 250.4(3) Bonding of electrical Equipment and 250.6 Objectionable Current.
Why would two parallel paths be required back to a SDS source in a case when the source is outside and required to be earthed and bonded to the transformers enclosure?