Real Estate - Hiranadani Upscale project in OMR

Dear Friends

I am living in Zambia. Was back from chennai after a months vacation. We are planning to book flat in Hiranandani upscle coming up in OMR front of Spicot estate. The project sounds good and the rates are thought a bit in the higher side for the Aminities it is good. But unfortunately we didnt find time to get a Legal opinion with our lawyer because of time constrain. But 2 things bother us
1. the builders say they have got height clearanc for 28 floors but no DTP apprroval and CMD apprroval. they say they are waiting for it and will get it by august . They showed all Banks clearance for loan aprroval.
2. They say they will give a builders agreement only when 20% is paid in full .

We are bit sceptical about it. And we went throught all of their projects in website. They r really good and atrractive.
We are confused to proceed or not. So any friends out there who had bought a flat from them or had any bitter experience with such builder kindly advise me.
Is anyone there buying in same UPSCALE.
I found a blog in Sulekha.com on another Hiranadhani project Palace gardens that there are some litigation in the land aquired do any know about Upscale project.

Regards
Sumati