If you're going to get this deep, then you also need to look at not just how a player feels at the conclusion, but how they felt in game, and how they feel ten-years later. During play, they may be having fun and not really consider it railroading. Once the campaign is done, they may sit down with another player and start to believe they were railroaded. Ten years later, they may reflect fondly on the campaign and not remember the railroading at all.
That is the problem with feelings, they change based on who we're with, where we're at, and the amount of time that has passed.