Hi to All,
Found this Forum interesting. I love running outdoors and unlike some of you that get into the 'zone' and don't even notice the surroundings, that to me is the whole fun of it, I don't even like to wear an MP3 player or anything as I like to see and hear all the surroundings.
However I have a treadmill in my house also, and I use that (don't like the gym habit of sticking a treadmill in front of a mirror, I do not need to watch myself) - usually set up so that I can see the tele or at least listen to music. I have used it to get ready for a couple of marathons also - the Shakespeare marathon in Stratford-Upon-Avon has a long dull path called the Greenway for the last number of miles which does the head in of many runners, however I say if you can run for an hour or more on a treadmill, you are mentally strong and prepared for anything.
As for the initial question raised, I also am a person who can always run faster outdoors than on a treadmill, I have always put it down to the the 'harder' ground outside giving greater impetus to the speed.