There's not many single mode or even basic 2-mode headlamps on the market anymore.
Take a look at the Petzl Pixa series from their professional lineup to see if they are in line with what you're looking for. They're 2-mode, simple interface, ruggedized headlamps intended for safety-critical applications like mining (also rated for use in potentially explosive environments). Output is low by today's standards, but high output is not what they're designed for.