We tried this on our client store.
The WP to XF registration works, but however, with complex passwords, this doesn't work. The developer was ready to solve our issues but the feature we wanted was not available with this plugin. We were also not interested in giving the dev our website access since it didn't work out of the box.
Anyways, the plugin was purchased and it's of no use to us. The developer is not ready to offer a refund.
I can see a lot of potential with this if it offers a reverse compatibility, I mean if it can sync xf registration to wp that would be great.