Cast Iron Pot - Cold or Preheated Oven?

Here's why, I think.  The closed hot Dutch oven does two things you really want:  first, it quickly produces the steam that you must have to strengthen and thicken your crust; second, it more quickly then forms that same crust, thus sealing in a moist crumb.  Neither of these things will happen as quickly in a non-preheated DO.  

I do know that I've read that people start from a non-preheated point and like their results, but I've never seen their photos.

How were you planning to use a DO with pizza?

to not subject cast iron to thermal shocks. It's easier on the empty cast iron pot if you start it in a cold oven and then heat it to 500-F. If there is a defect in the cast iron, it can crack when subjected to thermal shocks. It usually doesn't happen and people put cold cast iron in hot ovens all the time.

I've read hear and in other places that its not a good idea to heat an empty enameled dutch oven or risk it being damaged. That being said, I've done it a couple of times with no problems but thinking twice about doing it again. I will just use my standard cast iron DO in the future.

I have heated many DO's, enameled and not, to 550 without a single problem.  The enameled ones sometimes get stained.  This can be cleaned EASILY.  Interested how?  Just ask.