We used a db/seeds.rb file mainly for fake data to get our development environments going until there is real user data to work with. Can you use SeedMigrations to have a set of dev seeds vs prod seeds?
We didn't design the gem to handle "dev" data, the idea was really to handle "real" data, such as Product in our case.
Though if you feel like there would be a use case for dev seeds, I would be happy to discuss that with you (either here/twitter/mail etc ...)