I believe Arthur was of the same opinion himself, in the Forever Changes book he says he had to keep checking to make sure John Head was not Johnny Echols, such was his talent.
I was talking to Templo a couple of years back who told me that during the Baby Lemonade backed tours Arthur kept ringing John Head moaning about the guitarist in BL being a waste of space.
Apparently John still has Arthur's number in his phone, as a momento and reminder of their brief friendship (and of course, his son is named Arthur in respect and undoubtedly nicknamed 'arf-a-head' in school!)