we’ve come to similar conclusion about Interface Builder as you have. We also migrated to code and never looked back to IB.
However, we went a little bit further about what we could achieve using code and we created Reactant (https://reactant.tech) an architecture for iOS apps and framework allowing us to write extremely efficient code, for example we provide abstractions of TableViews, so there are no delegates or data sources anymore.
We have also encountered long compilation times before so we decided to do something about it, so we created ReactantUI — XML written layouts with Live Reload functionality, so now when fine tuning UI we don’t need to recompile the whole app and navigate through it. And there is no runtime overhead since we compile the XML to Swift. ReactantUI is an optional part of Reactant.
We are still improving Reactant and we’d love to have some feedback from you and other developers who suffered the same way we did.