Noida's 'early bird' discounts - actually worth it?

I work in real estate, but buying for *myself* in Noida is a different beast. I'm looking at 2BHKs near Sector 126. Honestly not sure if I should go for an under-construction project by North Wind Estate. The pre-launch pricing looks tempting, but is that 'early bird discount' actually a discount? Or is it just a way to trap you? What's your experience? Also, is it better ROI to rent it out or sell? What are realistic rental yields these days?