Yup, I had a look at both those Wiki articles (thank you Wiki, where would I be without you). On second thought I think I'll make do with volumes one and two, at least for now. I also saw his translation of Basho, but I think perhaps I might pick up "
Basho: The Complete Haiku" instead. Again, at least for now. Later on, when I've read Keene's first two volumes I should have a better idea how to proceed.
Thanks again Drake-san; much appreciated!