Hi Manish,
the advantage of the OData protocol is that it is becoming an OASIS standard while the MBO protocol is a proprietary protocol. This is also the reason why the future of SMP is based on OData.
For the next version of the OData protocol (v4) it is planned to support delta queries as part of the standard.
This is already now possible with SAP NetWeaver Gateway as described here in the Online Help:
http://help.sap.com/saphelp_gateway20sp04/helpdata/en/2e/d7d9ee0f0f4c3292a555ec1c2952b1/frameset.htm
And OData can for sure work without SAP NetWeaver Gateway. Just have a look at the site http://www.odata.org
We decided to go for OData because it is not a SAP proprietary protocol but is based on open standards like ATOM and JSON and will become a standard itself.
Best Regards,
Andre