All after more than one months R&D I finalise for two Samsung handset ie c6712 duos and wave 5253 and finally it was the brand or smartphone Bada os and 3-D surround sound 5.1 channel sound output and a price difference of 700 changed my decision to Samsung wave I have purchased it from letsbuy.com at a price of 5219 with 8gb micro sd, and disappointment comes while u browse video on internet connecting with pc , firmware update, else its a amazing phone with great features.
In samsung star2 duos c6712 its a dual sim with proprietary os but not a smart phone. and yes both support pdf docx exls pptx format so good for official purpose also.
But wave 525 is worth buying in 5500 fullest value for money as of 1 Sep 2011 in this price range.