Construction-linked plans aren't always better for investors

Spent the whole Sunday checking out options in Sector 111. Honestly, fed up of renting now, landlord raised rent again! Finally taking the plunge. Looking at Imperia projects there. My budget's around ₹1.8 Cr for a 3BHK. Is a construction-linked payment plan always smarter for investors than a down payment? Not sure if it gives real leverage. Also, how much does the super area vs carpet area difference actually impact the final price? Heard stories about builders inflating numbers. What about stamp duty and other fixed costs, can brokers help negotiate that or is it set in stone? Any recent buyers in Sector 111, what was your experience with payment terms and total acquisition cost?