I just today upgraded to a GTX 970, and decided to test the waters with GLSL and SEUS. Unfortunately, even using the 10.2 fix provided in this forum, I still run into a load of graphical glitches. Those include flickering shadows and a load of issues underground. Pictures related. As you can see, I've tried different shaders, and each of them provides a unique assortment of bugs underground.
I am playing FTB Monster 1.1.1, Minecraft 1.6.4.