The M11 has a long extractor, but all the P226 come with short extractors.  Why is that?  Is there a difference in the function or dependability of the two types?  

In fact, while you're here, is the Sig a controlled feed pistol?   Or, are some of the P-series pistols intentionally set-up for single loading rounds into the chamber from above?

Edumacate me, please, on the history and function of these extractors.  Thanks!

I've had the same question myself - sigtalk is an awesome resource for these types of questions. The main consensus is that there's absolutely no reliability difference between any of the P226 extractor designs - the internal of the earliest, short of the more-recent, and long of the most-recent. Any of them are rock solid.

Not sure what you mean by "controlled feed" pistol?

Controlled feed? as in bolt action rifles?

You can drop a round into the chamber just fine with SIGs. Not sure why you would want to but I guess its just as easy as topping off a mag. Not sure if SIG recommends dropping a round in the chamber or not. I have never had an issue when I have done so.

My p226 has a long extractor.