As promised, I searched NFPA and NFIRS for statistics on house fires caused by wood stove and fire place inserts. I found a NFPA report in 2010, page 43 ((broken link removed to http://www.nfpa.org/assets/files/PDF/OS.spaceheaters.pdf)) documenting the number of house fires for the period of 2003 - 2007, in which roughly twice as many structure fires were caused by (solid fuel burning) stoves than inserts. Interestingly, on page 32 of the report, all heating stoves were responsible for roughly four times as many fires as inserts, but that statistic included all fuel sources, and electric was the winner there by a wide margin.
Edit: Also noteworthy, I found other studies showing that the vast majority of fires started in the chimney connector or flue....and you guessed it, creosote build up being the culprit most of the time. However, I also found that there has been a huge decline since the early '80s in solid fuel burning appliance caused structure fires, so maybe we are getting smarter