I’ve been using the nightly releases for element X android for some time.
Sliding sync means messages are fetched quite a bit quicker, though it’s not yet feature complete relative to regular element android.
I’ve not yet tested element call on EXA, however, but it’s worked very nicely for me via web.
denender will suffice but the best protection is common sense. If for whatever reason you find yourself needing to interact with sus files there are ways to do so safely in a contained environment