Hi - IMHO, it is irresponsible for a hosting provider to offer a BETA version of an application for installation. My belief is that some people will install this version into production sites, then later get upset when it breaks, or serious issues are discovered and equally serious changes need to be made to a 'completed' site. Either way, this is still in the BETA stage, and the Joomla site clearly states that it should not be installed into production sites.
I can't say that "no" YouJoomla templates are or will be compatible with Joomla! 1.6; however, given the announced changes in 1.6, I doubt it. There have been a number of announced changes to templates and styling, and remember that we are still dealing with a product in its development stage, not a released product in its final form.
That said, I just downloaded a template (YouShows) and installed it into a virgin 1.6 Beta 2 install. The installation process showed a successful install; however, when I set this template to be default for the site, then visited the site, the site was broken. No shocker there.
In the template manager, things look nothing like they do in 1.5. So... It looks like 1.6 will need new and different templates.