I never heard of that Kiedis feud before but I have to say that without having the suggestion planted that they sounda like, I never would have said they are similar, and I am fans of both older RHCP and the multitude of patton projects. Really with how versatile Mike is, and how broad his range is, I'm surprised more artists don't think he is stepping on their toes.
I've been lucky enough to see both Fantomas and Mr Bungle. The Fantomas show was my favorite, partially because that was when Dave Lombardo was drumming for them. He did an excellent job of not letting the chaos get too uncontrolled and they gave him a nice long solo in the middle of the set.
Anyone check out the newest Tomahawk album? It's all "covers" of historical native american songs and it's really fascinating. It's a big step away from the previous two, but it's great and some of the drumming really pushes away from the boundaries inherent in rock music sound of the earlier albums.