I am curious about the implications of Rails migrations here. It seems that migrations give you a pretty good level of softness in your data models when you need it. Of course, I think a lot of Rails apps do end up with much of their logic in the M part of MVC. And understandably, some folks are not very comfortable with that.

Can anyone speak from experience on this? Talking about mature Rails apps now. Are Rails migrations a help or hindrance in terms of 'app aging'?