The debate is essentially a Gladwell (as "son-of-Rogers") versus Watts debate if you want the protagonists' version. I see it more about Taylorist approach versus the networked world. Gladwell, like Rogers, has pursued very eloquently the theory that messages spread through a hierarchical type of system. It is based on a number of key influencers who spread the word. This is what he calls the "Law of the Few" which posits there are a few specifically influential people who spread the word. While there is some social system consideration in this approach it is essentially, to me, one of control and organisations. Maybe this is why so many leaders and organisations have fallen in love with the theory of the tipping point - it gives them a handle on which to explain their process driven communication plans.
I have felt for a long time that Gladwell/Rogers is way out of date when it comes to communication. Much of the arguments Gladwell use come from the 1990's - and can you remember how you used to communicate on both a small and large scale back then? Much of Roger's research was done pre-internet.
So, on the other hand, we have Duncan Watts who is approaching the debate from a networking perspective. His work demonstrates we are as likely to get information form a fairly random contact as we are from a "key influencer". The Watts approach to creating a viral experience for a message is harnessing the power of ordinary people's networks and strategies. Sure, there may be some influentials who spread the word, however, what Watts is making us think about is this may not be the only reason message spread. Gladwell's theories and examples are presented as a hub and spoke model - whereas Watts uses a more networked model which to me seems to more accurately reflect my world and experience. The difficulty of course is that it is not as easy to design a message spreading program is we believe the spread is more random than controlled.
One example both have used is the famous 6 degrees of separation one. Each has taken his own perspective. Gladwell repeats Milgram's results. Watts tested the theory using email and found that only 5% of the messages spread through what might be called Influentials - the rest was down to ordinary and perhaps less connected people.
If I had to invest in a spread strategy I would be looking to create learning communities, to be harnessing existing online connections, finding ways to get the messages into the email systems, developing content that worked on an online format etc. I used to be sold on the Rogers then Gladwell format but my own action research has led me to lean more to Watts.