You also have to type, refactor, and test them. I work in multiple languages and the typed are definitely slower at the beginning, but pay off later. The strategy I outlined is the way to get the best out of both.

Also working in both I don't have this issue. I generally find types make refactors faster - I have less bugs from the refactor.

A mature refactor yes, a change in design often not.

> types as a first class construct

A wild Idris programmer appears