These new Triangular panels made me pretty excited at first, until I tried using them in the SPH and found the mirror symmetry feels all wonky and wrong for them, making it hard to design certain things with them.
Look at these screen shots - the mirrored symmetry isn't making actual mirrored parts. It's behaving just like radial symmetry:
The first two images are with Mirrored symmetry. The last image is with radial symmetry to compare. I don't see any difference.