Early in my drumming I was very impressed with Bonzo's single pedal speed. But I have to say that Nicko McBrain took it to another level. I still can't believe that some of the stuff on the "Somewhere In Time" album is done with a single bass drum and a single pedal. It is the fastest single bass / single pedal stuff I believe I've ever heard.
As far as good double bass drummers, has anyone mentioned Brian Downey? A rock shuffle master, he also shuffles the bass drums. Of course he also played straight double bass stuff too. Not fast by today's metal standards but very fitting to the music IMO.
Since we're on the subject of fast....I think speed is a lot like salt on food. Used in the right places at the right time, it can really perk things up. But use too much too often and it gets in the way and can be hard on the ears, IMO. But if speed is salt, then music is food and not everyone likes the same things. Some people love a lot of salt on everything, some don't.