The Phantom Menace Scrapbook specifically says each Sith in the Rule of two is stronger than the previous one, you can interpret Gravids' destruction of Sith knowledge of them losing knowledge but didn't stop their growth in power, which is what seemed to be implied since Plaguies was wondering about the lost tech such as drain life.
Gravid destroyed some knowledge, but Gean still killed him in combat (despite the cybernetics she needed afterwards), so yes, the cycle continues. Given that Plagueis muses that they're about 30 generations of Sith Lords between Bane and Palpatine, and each generation is confirmed by multiple sources to be more powerful than the last, yes, Palpatine, Plagueis etc. are leagues above Bane.