I really liked "Medieval Cities" and it has informed my thinking, but it'd be foolish to think that no further research has been done.
This post is confusing. The title is 'Pirenne Thesis' which is a reference to his thoery of transition from Roman to Frankish worlds up to 8^th CE (which is roughly summarized as 'Without Islam there is no Frankish empire; without Mohammed, no Charlemagne'). But your comment is about his theory of the 'resurgence' of medieval cities in 10^th to 12^th centuries CE.
Which are you asking about?