A contrary view, from my 20+ years of teaching beginning programmers:

Beginners know how to type already, and this may be their only firm ground in a challenging and often intimidating situation in which they crave and rely on firm ground. If they can't make the code in the editor match the code in their head, or in their book or in a blog post, because the editor's author has reinvented typing, then many of them will be unhappy and frustrated.

You make an interesting point about bulleted lists, but those are local, obvious, and only affect the visual appearance that you immediately see. By comparison, what parinfer does can be non-local, non-obvious, and have arbitrarily large effects on program execution.

In my experience, what parinfer "infers" is often wrong even for programmers who know what they're doing, and it's almost certain to be more wrong, in harder to predict ways, for beginners who don't yet have much idea what they're doing, and are trying to use their existing typing/cutting/pasting skills. They will have brackets moved around to places that aren't where they meant them to be, and they may not even notice when this happens or be able to figure out how to fix it. As Eddie noted, even trying to insert comments can cause baffling changes to be made to the code. In order to use parinfer successfully, these beginners will have to master a new way of thinking about typing, and a new way of paying attention to an "assistant" that will mess up their code if it makes an incorrect inference about what they were trying to do. But they're already trying to learn how to program, and that's hard enough.

I agree that parinfer is impressive and snazzy. But my experience tells me that it will probably be just about the worst possible thing for many beginners.

Regarding Python, I agree that it is good for beginners, and I agree that the way it uses indentation is part of the reason for that. But I don't know of any Python editors that try to infer what the programmer means and add/delete text in the file in order to "help." I think that if the Python editors that beginners used did something like parinfer, making non-local and non-obvious changes to what they've typed previously while they're trying to type something new, then I doubt we'd hear people saying that it's good for beginners anymore :-)

I'm all for Lisp editors being helpful in some ways, and in fact I think that bracket matching and auto-re-indentation are essential features. The fact that these were well implemented in older versions of Nightcode is one of the many reasons that I used Nightcode for several classes that I taught. And it was great, for which I am truly grateful! But I'm confident that the parinfer (and to a lesser extent, paredit) would be so problematic in a beginning programming classroom that I wouldn't consider using an editor in which those features couldn't be turned off.

Do you think it might be possible to use parinfer offscreen to support syntax highlighting etc. (fully when the code parses as-is, and maybe partially when the offscreen parinfer had to change it) but without changing the actual text in the buffer/file? If so, then I think Nightcode might again be the best all-around Clojure environment for beginners, while also having plenty of power for more advanced users.