Each setup is different, there may be issues with syncing but we'll need them reported before we can act on them. To my knowledge I don't see any issues from you (not saying you didn't just don't know what issue you have, a link would be great)various issues reported here when syncing users, threads etc
Thats the point no? A unified thread design and experience. I mean you arguable could add some CSS just for the wp articles, should be easy enough. Something Im missing here?no possibility to style the Xenforo threads showing up under WordPress articles as they are entirely controlled by XF and only styled properly when using XenPress theme
I mean, we could go down the rabbit hole of building every single tool one could ever want in the world, but I don't think it fair to fault us because we don't have disqus migration support to XenForo? :/no possibility of importing previous WP comments into Xenforo thread display, reverting to WP default comment or disqus ->ending up having thousands of comments displayed in a different way, creating a confusing end-user experience ("why is there a thread?", "why is this next article connected to a discussion forum whilst the other one is not?" etc.)
I think migrating comments to existing threads is rather difficult too, not saying we won't do that but again, its a feature that may be nice but was never advertised that it did this.
problems/issues when trying to connect a new/and or existing wp article to an existing xf thread
Again, link to issue? I don't know what it is offhand. I've tested this myself in the past, worked fine. But if we need to fix something, happy to. Just don't know what its doing for you, as for others it works fine.
display issues when wordpress themes/plugins also use font-awesome icons (->noticeable both on backend and front-end)
That is going to happen. It is impossible for us to know how each addon/plugin you have sets up FA. Simply disabling it at the theme or XenForo level will work.
the biggest problem: broken wordpress caching and minification ->> the absolute deal breaker
We added some new caching tools in the latest release (not sure if its the next release or one currently released, tagging @Lukas W. ) but in the past I agree it was not ideal, so we spent a good month or two fixing it. Server side caching is recommended, but we do leverage XF caching as well. We cache whatever we can.
support was "friendly" but not really fast or helpful
Apologies if we didn't answer all your questions. Here to help if we can.