No work required for the currently released versions and the updated version of XenBase so that's a good sign .I just upgraded 4 forums to XF 2.1.8, all using customized versions of Flat Awesome +.
No errors. No templates needed to be reverted.
I can confirm, no issues/template reversions with 2.1.8 or 2.1.8 Patch Level 1, whatsoever, with the templates.
There's a nice battle raging over on the XF forum relating to TH styles breaking established add-ons. It's a pleasure that no such drama exists with @Russ and @PixelExit.
Thanks to all of the PE crew for making such a quality product, and supporting it with EXCELLENCE.