Noida Extension RERA checks: Investor's big worry

Spent the whole Saturday checking out options in Noida Extension, including Deepak Green Residency. Fed up of renting for years, so finally taking the plunge. My biggest concern as an investor isn't just ROI, it's the legal stuff, yaar. Builder ka track record aur compliance sabse important hai. How do you guys *actually* check a builder's RERA registration beyond just the number? What are the real red flags to look for regarding Subhlaxmi Developers specifically? Is there a solid way to verify their past projects for legal issues or delays? Also, encumbrance certificate kitna important hai before making any substantial payment? Don't want to get stuck later with title issues. Any practical tips on these legal checks for Noida Extension properties, especially around Sector 137?