ColoradoStoneman
Newly Enlightened
You must understand it's quite complicated to reduce the light output from an LED while maintaining it's output characteristics. If you simply reduce the supply current to the LED, the tint will shift. So most of the multi-output LED lights have an microprocessor inside that turns the LED on and off very fast in order to reduce the lumens output. In technical term, it's called the duty cycle of the Pulse Width Modulation (PCM).
Now in a variable output light like the T1A. The microprocessor must continuously monitor the bezel dial, and adjust the duty cycle on the fly. So the software is far more complicated. There must be a digital rotation sensor so the microprocessor can read bezel position. (Microprocessors can only read digital signal, so you can't just use a cheap potentiometer, unless you use more expensive microprocessor that has a built-in Analog-to-Digital Converter). All this technologies, pack into the head assembly, that's less than 2cm diameter x 2cm tall.
Fenix PD20 $55 - Surefire T1A $240. Both have PCM circuits. Fenix has logic to read the clicky, to change modes. Surefire uses a potentiometer. I would say firmware complexity is a wash.
I not sure an extra $185 for a potentiometer, explains it. Beyond that, having a weak link like a potentiometer in a flashlight, is not exactly a good idea for "Legendary Reliablility".