The Kemet film caps have improved the sound stage, 3D imaging and extensions of the lowers & bass. This direct-out mod itself purifies the sound and renders more details. But during that process the caps make a big difference from my experience.
Modding the 5.5g's has brought me the fun and rewarding experience.
I also have and still own a RX MK2, but the Leckerton is clearly the winner in my opinion.