ORM[suggestion]

The benefits of an ORM depend primarily on the complexity of the data (and the complexity of the ORM itself). If your data is fairly simple to work with, an ORM might be overkill for your application. Rapid prototyping is only really relevant if you find yourself writing large amounts of model code which do nothing more than store/retrieve data when you don't use an ORM. If your data is relatively simple, it's possible that you could improve the speed of development (even beyond prototyping) without resorting to a complicated ORM by utilizing a more robust base model or using some sort of code generator.

In an environment in which use of a particular ORM is optional, as would likely always be the case for CodeIgniter, it becomes an architectural choice. If it doesn't make sense for a particular add-on to use the ORM, why would you choose to use that add-on?

The reality is that anything which uses a given ORM for something simple is quite easily rewritten to use Query Builder or raw queries. It is only when the ORM is actually justified or when the developer's database structure is more complicated than necessary that it becomes difficult to separate the two. In the latter case, you don't want to use the add-on at all; in the former, you are unlikely to see the ORM as the bottleneck.

Bonfire

Practical CodeIgniter 3
CodeIgniter Testing Guide