I have updated a number of Weaver sites to WP6 without any problems so far. All of these are using the Xtreme Plus plugin and are running a variety of other plugins, quite a lot of variation across the sites.
As far as I know, the current Weaver Xtreme theme has no issues with WP 6.0. I have been short on time to update the current version of Weaver Xtreme, but for now there should be no issues.