I once worked at a company where the policy was: you can select anything you want, but database updates/inserts are always done through stored procedures. I think the point of preventing developers from doing any update/inserts was to insure that only "logical" (and documented) entities and relationships could be committed to the database
Where I work now, I've noticed a tendency for entities and relations to creep into Perl code - you see things like testing where a product_type is a certain subproduct type and then doing a certain set of insert/update operations as opposed to another.
DBIx::Class is a wonderful tool. Powerful, support for many databases. Large user commmunity. That being said, I think it can be tempting for "entity-relation creep" to occur with it and it should be restricting to using entities entirely modelled in the database. Why? What happens if you decide to write some code in a different language? The more that's in the database, the more that each language can share.