On the recommendation of my groovy boss, and he should know as he 'was there' during the 60's and all it's social,political and musical change, starting his company in San Fransisco .... I bought a double CD encompassing 2 albums by Butterfield and his band:-

The Paul Butterfield Blues Band 1965
East - West 1966

Butterfield can certainly play the blues harmonica, the make he used during recording is even credited in the sleeve notes; 'Paul Butterfield plays the Hohner Harmonica's'. I do love the harmonica and for a very short while, tried to play it. I love the imperfections of it and the gutteral sound when the player both takes a breath and plays, it's a deep, throaty sound which comes with such force. I also love, what I can only describe, as the 'fudged' sound when a piece is played to extreme.
I read that Butterfield sounded black, not so sure about that. During the bands time he had members from Howlin' Wolf's former rythm section: Sam Lay - drummer and Jerome Arnold - bassist. Good influences I am sure but the icing is undoubtedly Mike Bloomfields incredicle guitar playing which could be viewed as somewhat intrusive [in fact one the members of the band continually complained about it] but he plays with such natural ability and conviction. Worth giving these albums a listen just for his contribution. In fact, have to say that I preferred the instrumental tracks better than the vocals.
Butterfield happened at the right time. His dedication and the intensity with which he delivers bought modernity to the blues which must have rocked the US blues scene in the early to mid 60's.

Tracks of note:
CD 1 I Got My Mojo Working and Our Love Is Drifting
CD 2 Walkin' Blues [by Robert Johnson] and East West which is a really long, acid driven and divine pyschodelic piece - FANTASTIC!
Interstingly there is a track written by Mike Nesmith called Mary Mary. When Nesmith recorded it with the Monkess, there was outrage as they were accused of covering a Butterfield track!

"I got a mind to give up living, yes, and go shopping instead".
I Got A Mind To Give Up Living.