My experience is that declarative starts getting mind-bendy and awkward past a certain point of complexity. It’s nice when it’s simple enough for everything to fit on a single screen without too much scrolling, but past that you need to start breaking it out into separate files. That’s not too bad initially, but eventually you end up with an infinite-Matryoshka-doll setup which sucks to navigate for anybody who doesn’t know the codebase because they have to jump through 7 files to drill down to the code they’re actually interested in and makes it more difficult to get a thousand-foot view of it all.
Also, the larger the project the more likely it is that you’re going to have to pull off acrobatics to get the desired behavior due to the model not cleanly fitting a number of situations.
Declarative is solid for small-to-medium projects, but for more “serious” desktop class software with complex views and lots of panes and such I’d be reaching for an imperative framework every time. Those require more boilerplate and have their own pitfalls, but scale much better on average for a dev team with a little discipline and proper code hygiene.