Something to consider for people interested in Sequel. Sequel is great and all, but it still follows the Active Record pattern (Sequel::Model), not Data Mapper. Also expect to run into some problems with gems that interact with ActiveModel (Devise, CarrierWave, etc.). It's all solvable of course but it might require some hacking. Most popular gems have sequel versions or ship with sequel support, but it's not as well tested and maintained, we had to contribute several patches. Also, if you plan on using Sequel with Rails, don't use any of it's plugins that make it behave closer to ActiveRecord. Stuff like nested_attributes, delay_add_association, association_proxies, instance_hooks. They seem really nice at first, but I guarantee they will cause all sorts of unpredictable problems down the road. I would recommend looking into something like Reform which decouples form logic from your models because working with complex forms is going to be harder without all of the AR magic.
Sequel::Model's quite optional - it doesn't force you to use the AR pattern. It's built on top of Sequel::Dataset, which is entirely usable all on its own.
It doesn't force you, but you lose all of it's ORM features. Sequel::Dataset is basically just a query builder so ROM would probably be a better choice then yeah.
