Clipping Section: Switchable between silicon clipping, as in the classic RAT, and a mosfet/germanium clipping section, which is entirely new to the RAT line. The mosfet clipping section gives you subtle scoop and smoothing in the upper mids throughout the entire gain range of the pedal, and makes the pedal sound more amp-like and natural.
Socketed Opamp: The pedal will ship with the current stock chip (OP07DP). However, changing over to the mythical LM308, or other compatible chips will be a quick and simple mod that you can do solder-free.
Large, CTS Pots: They give you a smooth, even sweep throughout the range of the Distortion, Filter, and Volume controls, allowing you easy access to the myriad of sweet spots in the tone machine.
Fat Switch: Provides a significant bass boost and simultaneous high cut. this makes the pedal more suitable for bass guitar, lower tunings, as well as fattening up and smoothing low gain settings, making this a good candidate for overdrive use.
9-18V Operation: Increased headroom and fidelity with 18V operation and less sagging as compared to older RATs.