@Drew-Llewellyn nope not for me, I'm surprised Nodebb developers have not complained about the security risks.
They were quite stringent on this in the beginning.
There is no preview either, maybe if it had that I would use it. There would be a lot of messing around if you didn't get all your html right the first time, and there really is no way to test if it works, so it gets published straight to the forum. Modern day forums allow preview's before finally submit the real thing.
I did discuss this with @julian by email. There was a one month grace period where we could return Redactor for a full refund, so we took the opportunity to explore it and assess it for security concerns like script injection and iframe manipulation. We were happy it is secure.
For the preview, you'll note that the preview currently provided is a different font size the the actual post, and @ mentions don't have the same colour as they will in a post, the background colour is different and large quotes that get 'folded up' in the actual post aren't folded in the preview. So I would argue that Redactor's WYSIWYG editor is more accurate in its preview than the default composer.
If it's not for you, you don't need to worry as the markdown based composer is still available and supported. For other people who want rich content and more style options this is probably more for them. Especially people who are running forums where the initial post is staff-written content. Any company wanting to put together stylish, eye grabbing posts will want more than just markdown provides.
Thanks for giving it a test drive and providing feedback.