Sakuraba is probably my all time favourite, but I think he is rated where he should be. He was sort of the generation of fighter's that linked the old school UFC/Gracie era to the modern MMA. He never really had a sustained period of dominance over other elite fighters, BUT he deserves legendary status for doing what he did to the Gracie's, consistently fighting undersized, his innovation and for being an absolute warrior.
I think his match with Miller is going to be amazing. I can't think of anybody better than Mayhem to showcase Sakuraba's abilities, even though I think Miller will probably win.