Damn, Unpoly looks great! Never tried HTMX but have been a fan of it, it solves a UX problem that frameworks like Django and Rails suffer from, without needing to bring in something heavy like React.
I'm currently working on a side project in Rails using Stimulus but sometimes I wonder if Stimulus is overkill with all of the controllers and stuff as well. Do you have an opinion on when you should reach for something like Inertia or Stimulus over htmx?
In most simple cases you probably don't want to be handling request-response initiated DOM updates in a Stimulus controller. Turbo Frames and Turbo Streams are the more htmx-like in functionality and they're excellent for this.
I think the htmx counterpart from Rails folks would be Turbo not Stimulus