Investor's dilemma: Payment plans and spot discounts in Greater Noida?

Spent the whole Sunday checking out options in Kendriya Vihar. I'm currently in a 2BHK in Sector 137, thinking of upgrading to a 3BHK for investment. Visited Krishna Vatika Society, they're really pushing construction-linked payment plans. Is it smarter than a down payment option for an investor like me, considering the current market near Yamuna Expressway? Also, how much spot discount can one realistically push for in Greater Noida? Do builders like M3M or Godrej actually offer good spot discounts or is it mostly a no-price-drop policy? Which approach would you guys recommend for maximizing ROI?