My Magnifica moved to a spot where my BTA's were thriving (I guess the spot was a good nem spot). One BTA moved right away, the other battled for weeks and ultimately almost died. It moved finally and is browned out, lost a lot of tentacles, and seems to be on the brink of disaster. It was pretty stubborn and wouldn't move. I don't think they can touch, but they can coexist. The magnifica would win every time, just depends on how badly the BTAs would want to fight.
Oh yes, a mag will beat a BTA in a fist fight almost any day. Mags are much stickier and pack a more powerful sting. I have never felt a BTA, but my mag leaves a little red rash on my forearm when I brush against it.
Is your BTA getting any better? Or is it continuing to shrink?