My 2 Cents wrote:
I'll admit up front that I can't directly answer your question as to who Pfitzinger has coached. But, I can give you some personal experience having read the book and applied a great deal of the training outlined in his book (for the marathon).
I found that while I ran well in the marathon (2:24) using his more "speed" based philosophy, I ran better once I went to a training plan that incorporated more marathon pace training (2:19 PR). Now, perhaps I ran faster because I was more experienced and had more years of training under my belt, but I feel as though perhaps Pfitzinger doesn't focus enough on marathon-pace work.
This is similar to my experience (though my times are slower). Following the Pfitzinger plans I ran 2:32 and 2:29. Once I bought Arcelli and Canova's booklet from the IAAF and started following the advice in there I took my times down to the 2:24-2:25 range for the next few marathons I raced.
The big differences I noticed were that Pfitzinger had folks going from 1/2 marathon pace tempos and 90% MP long run workouts early to really focusing on 5k/10k type workouts in the final 6-8 weeks.
On the other hand, following Arcelli and Canova's advice would have a running similar stuff early on (with a bit more of the faster work done there), but spending the last 8 weeks focusing almost exclusively on near marathon pace work for the quality sessions.
I suspect that the Pfitzinger style plan might work well for someone who is a mega-slow-twitch type of runner, but I'd bet that for most others (and certainly for me) the Arcelli and Canova style training works much better.