Here are a few thoughts on the interesting discussion that has developed around this subject. Unless the subject is defined clearly, the discussion will be just as endless as history itself. And not having tractors is certainly an important ingredient in being medieval. There is a useful sense in which Casassa's italian farmers and Lewis' texan ones deserve to be distinguished from medieval farmers. Just because all of them don't have tractors doesn't mean they are similar in other respects.
Technology surely is a very important factor.
But its tangibility ought not to prevent us from recognizing the reality of less tangible but equally important factors. I know a woman in Bavaria who also didn't have tractors until recently and when I visited her from the US for the first time, she asked if one could take the train there. It is very easy, and very wrong, for us urban dwellers to believe that all people without tractors are basically alike. They are not. Maitland said that it was Sir Henry Spelman who introduced the feudal system into England.