El Yucateco Kutbil-Ik Habanero Sauce is absolutely delicious, however, there's an obscure sauce from Mexico that's of the same style (traditional Mayan hab sauce) but even BETTER.
http://productosmari...lsas/index2.php
http://www.yucatanpr...as_kutmarin.php
El Yucateco's sauce is 10,000 SHU, while I estimate that the Marin Kut Habanero Sauce is about 50,000 SHU, if not more. I also find that while the Marin sauce has a more watery consistency, it seems "fresher," and the taste is noticeably better than Yucateco's rendition of the ancient Mayan recipe. Definitely a lot more hab flavor to it. Yucateco's sauce, while yummy, is a little overpowering with the spices.
GOOD LUCK in getting a hold of this sauce. Unlike El Yucateco's products, this sauce seems relatively unknown and difficult/impossible to find outside of Mexico and bordertown USA. I only had it because my parents brought it back to me as a souvenir from the Riviera Maya.
Summary: Both are good renditions of the traditional Mayan habanero sauce recipe. However, the Marin version seems to be more faithful to the cuisine of the Mayans, both in heat and habanero flavour (consider that in Mexico, the sauces would be fresh and therefore fruity). El Yucateco is more on the commercialized side of things due to its toned down heat level and mass availability.
NOTE: I am not hating on El Yucateco's products AT ALL, as I do enjoy their sauces and would recommend them to any hot sauce enthusiast. However, I do believe that there are better and more authentic Mayan-style "Kut" sauces out there. This genre of hot sauce is by far one of the most poorly understood by chiliheads, and there needs to be a lot more exposure. For most people, El Yucateco is the only Kut sauce they'll ever get to try.