Excellent post, @Mike Lambert! I lived in the area for 7 years, own several properties in Tulum, and manage a portfolio of vacation rentals there as well. What you're saying about the importance of vetting the developer is essential. We had a LOT of challenges with a developer that turned out fine in the end but created a lot of stress, delays, and challenges along the way, especially in terms of accountability and finish quality.
Another dimension of risk that few people talk about with Tulum is the ecological destruction, particularly of the cenote system. The environment is the #1 driver of tourism to the region and it's not adequately protected. My hope is that all the money invested in Tulum will lead to significant infrastructure upgrades and investments either by the government or private industry if things get really bad. Without Tulum's beautiful beaches, cenotes, and jungle, why would tourists come?
The other risk with Tulum is that, in my analysis, the resale market can be really tricky. With so many presale opportunities, why buy a property that's 3-5 years old? Many existing properties sit on the market for a long time or have to significantly drop their prices in order to sell.
All that said, I think there are some great investment opportunities in the area! Investors just need to look for unique opportunities that can compete in the current market.