Based in Xilitla rather than Ciudad Valles, which puts them at the southern end of the region and closer to Las Pozas, with their own guides rather than subcontracted ones and departures every day.
Their guides are certified to NOM-09, the Mexican adventure-tourism standard, and they carry insurance — both worth asking any operator here, because the waterfall jumps and rappels are not decorative. They also run departures from Ciudad Valles.
No street address is published, so this is pinned on Xilitla.