Hi Harish,
on the GS1-side , there is a pretty useful Implementation Guideline for AS2
http://www.gs1.org/docs/gsmp/xml/sbdh/Newcomers_to_AS2_Implementation_Guide_i1.pdf
In Chapter 3.9 , it includes all the different parameters that should be exchanged between you and your trading partner when you agree to use AS2 as the communication protocol.
Other than this, I think that AS2 is a very good protocol and hihgly standardized and this is also why it has been applied by so many companies.
A (signed) MDN should always be used in my opinion, as this then guarantees to the sender of a message, that the file has been received successfully by the recipient..which the recipient then confirms wit ha signed messages.
