Bill is indeed a rare treasure in the world of music and percussion specifically. He is a true artist in that he needed to be challenged and like all great jazz musicians he liked to surround himself with musicians as good as or better than he.
I've had the pleasure of becoming an acquaintance through his long time friend Mike Shore. I've seen Bill perform in 2 editions of King Crimson, Genesis, UK, Bruford, The Jeff Berlin Group (a short duration ensemble with Jeff on Bass and Randy Roos & Mick Goodrick on guitars - in a tiny club that seated about 50. Bill told me he flew over to Boston, rehearsed all new music for one night then played only a few shows in Boston then Cambridge), Yes, David Torn Group, Bruford Levin Upper Upper Extremities and 2 editions of his Earthworks. I might have missed one or 2 more. At one time I think that I counted 13 different bands with which I saw him perform. He also played with National Health and several other bands.
Sadly he has put down his live performance sticks, but look at any video and listen to all he's recorded as he is a standard for which most drummers should aspire. I miss you Bill.