Steven Moffat's strengths lie in a really strong ability to experiment and play with time as a storytelling device. Girl in the Fireplace, Silence in the Library two parter, Christmas Carol are some strong examples.
He also has an incredible ability to tap into the human psyche to invent some astounding villains; the Weeping Angels, the Silence aliens (not the Silence religious movement), the Clockwork Androids, etc.
And the man has great structural, comedy, and thematic sense, as a well as a Joss Whedon sense of deconstructualism.
But...
I don't know if those strengths are good for a Producer of a "long form" series (long form as in 13 episodes vs 6 episodes like in Coupling or 3 episodes like in Sherlock).
He has a strong concept but it ends up stretching it way too thin over a series.
Moffat should write the first episode and the last episode and then hand the slots over to a stable of strong writers who can take his ideas and themes and run with it.
I had my issues with Russell T Davies as a writer but I think he was phenomenal as a Producer.
My dream team would be Davies as Producer and Moffat as Head Writer.
