Honestly interested in your experience.
I am not surprised around (1). HTMX is based on REST, which is by nature based towards having the state in the server and having a stateless client. But what is the advantage of having the state in the client. Isn't that just a bias of the current frameworks?
I can see cases where you really need a thick client, and in that case I would use GraphQL rather than REST for those. But, there are quite a few cases that can work with REST and mostly server side.
I think (2) is solved by out of band capabilities of HTMX. I don't think that is naturally a limitation of the conceptualisation.