Never saw this post, but my 400 gallon is 200 cm wide and the left side is 80 cm and the right side is 120 cm deep, so the front pane is diagonal, just not 45 degrees, but 20 or so.
Till now i only seen real examples from rather large tanks... Quite a difference in glass thickness, makes diagonal seems a lot stronger.. I'm curious how that will work in less thick glass on the long run. Just for safety i might just need to go for minimum of 8mm glass. With the optiwhite option this might be the best choice. 🙂