An Apology
It is, of course, completely correct that the Feudal system of obligations does not apply to serfs.
Large scale serfdom does not show-up, however, until after the Black Plague and is primarily limited to Eastern Europe.
Peasants are included in the system of obligations, something which is particularly apparent in the dark ages and and early to high middle ages. Or in England, France, Spain, and areas of Germany after the plagues.
The peasant revolts and the less national elements of the Reformation are very often reactions by the peasants against forces which were enfringing their growing power.
I've got nothing against Sweden and would never argue that a peasant is better off than a modern Volvo factory worker in a general sense. There are comparative advantages. But one could argue that such things show up in any comparison of systems. I wouldn't.
I don't think I'm romanticizing the system. Feudalism was a large and varied idea with a long history. I'm merely pointing out that no system that is as popular or successful as Feudalism was has existed without bringing real benefits to all the people in it. Particularly in time periods that lacked the technology or moral framework to make totalitarianism work.
Certainly calling it a system of large scale slavery would a distortion of the truth at least as egregious as if I had said that were blessedly protected and the nobility lived lives of constant warfare on their behalf.
Further, actual systems of large scale slavery are often much worse than even the serf system of Russia or Prussia. A noble might effectively be able to ruin a serf, but it is very difficult, legally, for that noble to remove the serf from the land he works and the family who raised him. Whereas, someone who was owned by an American farmer from Virginia was a proud member of the estate of mobile property and could expect to be sold away from his or her family and to have every expect of life at the mercy of arbitrary whim, with no real recourse to revolt.
Peasants can very effectively work to make a local lord's life and office untenable, where else do bandits or someone like Thomas Becket come from?, but slaves have no such similar strategies to work with.
As to my research, well, I would recommend the documents from Lateran Councils I-III, any English Book of Days, and any number of scholarly documents dealing with peasant revolts under Richard the II. These are all available in English and, absent the presence of a good professor of medieval or church thought, history, literature, philosophy, economics, or technology, are a fine means through which to approach the primary sources of the period.
Plus we were talking Lawful Good, were we not?