I haven't seen the Jardine book (but am interested). With regards to Erasmus, he might have been good at self-promotion, but his importance in the post-medieval humanist tradition cannot be denied.
I think that one of the most fascinating aspects of his life is his friendship with Thomas More, someone else usually described as in the "humanist" tradition. When I was young, More became close to a hero when I saw "A Man for All Seasons" - I think this was a film that affected me greatly when I first saw it, around 12 years or so.
Recent knowledge has severely dented that early enthusiasm however, specifically relating to his hounding of the great Bible translator William Tyndale. More's very coarse and brutal language against the "heretics" who dared put the Bible into the English language is shocking to read.
Is this Erasmus' friend? Tyndale, although not a friend of Erasmus, was close to him in spirit. Erasmus' translation of the New Testament from the Greek inspired much of what More would rant against.