Yes, I still love my Montana Markers.
Yes, I did go out and buy the 15mm wide tipped versions of my two favorites, white and silver.
Yes, using a wide marker DOES change the way I use the ink and make the differences between negative and positive space ambiguous.
Also, I did some drawings on some interior office windows that people kept trying to walk into, and the ink sticks beautifully to clean, smooth glass. Yes, my colleagues all came by and touched it (gently), and it held up really well. Yes, I am afraid I'll buy lots of transparent films and draw on those now - thanks for asking!