Huh? lit-html uses standard JavaScript. That's it. JSX is a non-standard extension. So yes it is more standard than a non-standard, and lit-html runs directly in browsers without any transpilation while JSX very much doesn't.
VS Code is as able to analyze lit-html templates as well as JSX via the lit-plugin extensions. It gives you type-checking, code completion, hover-over docs, and linting.
Yes, JSX needs transpilation but that happens at compile-time. Which is better, pre-processing at compile-time, or "transpilation" (i.e., string processing) at run-time?
Updates offered by lit-html appear to be very limited. If you change value of expressions it updates the DOM. What about larger changes, such as list items changing? What about child elements being replaced with new ones?
update() simply iterates through each part and value (the parts array and values array are always the same length) and calls part.setvalue(v) for each part.
Behind the scenes lit-html creates HTML <template> elements from your JavaScript templates and processes them so that it knows exactly where to insert and update the values from expressions.
This is very limited. You need to manually update DOM unless your updates are simple changes in values of expressions.
It is very correct: lit-html is amongst the fastest template systems in use right now. This is shown in every benchmark I've seen or made for it.
lit-html updates only the parts of DOM that are dynamic and change. It handles nested templates as values, only updating the whole nested template if the template itself changes, otherwise recursing and only updating that template's values if needed. Repeated DOM is handled either by simply updating state for each item in sequence (non-keyed), or by using the repeat() directive which will move DOM (keyed).
You absolutely don't need to manually update DOM. The whole point is to describe your DOM structure as a function of data, and to be to describe all the conditional / repeated parts in the template expression itself.
OK, so plugins can enhance code editing. But what about compile-time checks? With TSX, if you have a mis-matched tag the TypeScript compiler will give you an error.
LitElement + lit-html give you very efficient updates, and don't require non-standard JS like JSX.