@jdaviescoates Yes I still use mainly Collabora with Nextcloud and I have noticed tremendous improvements, especially since NC and Collabora have worked together to improve the integration.
However, I wouldn't say it is still quite like Google doc, or quite as fast as OnlyOffice. I tired OnlyOffice when I installed CryptPad and something about it feels more responsive than Collabora due to client rendering. It is basically just like editing on a desktop and Collabora is not quite there...but pretty close. Also we can feel that both Gdocs and OnlyOffice were designed as a collaborative editing tool whereas Collabora somewhat inherits the LO single user approach and tries to adapt it for collaboration and the result still does not feel quite as sleek....but here again it is getting much better than it used to be.
I can say that Collabora does not suffer from issues from the past, does not feel laggy and is perfectly fast enough to use while not feeling it's slow or weird. Also I do think it provides the most complete online office suit in terms of functionalities, and the best if you using open document formats.