I use both FB and Twitter a lot, yes.
The niche of my community has a single well-used hashtag so, when, a particular discussion on the community platform is proving popular, I will use that hashtag and ‘trending’ with a link to the discussion thread and post to Twitter. I mix up the posts - sometimes just text and sometimes attaching a relevant photo.
If there are a few ‘trending’ conversations I queue up tweets in buffer to my pre-defined schedule rather than push out multiple tweets around the same time.
I do similar with Facebook, but less frequently.
I also push out links to relevant and interesting content that I have curated, as well as using both channels to take questions and support matters from members of the community.