Maintenance vs. Development

For a colleague (Arun Gupta) who's looking into Ruby-on-Rails, I posted the following comment and question:

You might find APRESS' "Begining Ruby on Rails E-Commerce" useful. It covers quite a bit of ground while remaining focused on a full e-commerce application, containing all that is required in such applications, except perhaps, fancy user interfaces.

The question that arose in my mind as I read this book and played with the ideas contained in it was whether Ruby-on-Rails programs were any easier to maintain, and in general, what was the cost involved in maintaining them. Are we losing flexibility for maintenance as we gain speed of development?

I should have noted that the above book focus on using Ruby-on-Rails with MySQL. PostgreSQL also supports a relatively live and active Ruby-on-Rails community, particularly in Japan, I hear. Focusing on a particular DB supports that DB community. Note that the imposition of many relational constraints often require db-specific SQL. These DB specific SQL files can easily creep onto a Ruby-on-Rails project, defeating at least some aspect of its claim to DB independence.