If you don’t really need the features of xStream then I would stick with Infinite … maybe upgrade to 6.6 as the eco painting is a very welcome feature.
As for xStream, I am using it with C4D (R9.6) and have a LOT of issues, mainly the lighting and render settings (AO and GI) aren’t always compatible between C4D and xStream. Also, HAIR is a problem with xStream, since both are post-process … unless you generate polygons for the HAIR. Still, getting the mix of Vue lights and C4D lights working isn’t always the best.
Vue lights are limited in features, so if you want some specific area shadows, etc… you’re in trouble getting it right.
Combinations of C4D sky and Vue atmosphere is a problem as well.
Anyway, maybe I am just too negative as I have been using xStream for a year now, and have not been able to create a decent workflow. xStream is nice, but just too limited. Crashes have been reduced over the last releases (they still occur now and then), but still not as stable as C4D.
If there was an alternative to xStream, I’d probably ditch Vue … just MY opinion of course.