The Trijicon RMR Type 2 RM01 uses Auto-LED brightness control — an ambient light sensor sets illumination level automatically. The 3.25 MOA dot is the same precision-friendly reticle as the manual-LED RM06; the difference is whether you want to manage brightness yourself or let the optic do it.
Specs:
Auto-LED vs Manual: Auto-LED is the right call for duty/carry where you don't want to think about brightness when drawing into different lighting (going from bright daylight to a dim interior, for example). Manual (RM06) is the right call for competition where you want exact control.