One thing that can be changed in future tournaments:
Now in QF we use this format: A1-B2, B1-C2, C1-D2, D1-A2. In this situation there is a high possibility that two players who played with each other in group stage will play once again in SF. To exclude that possibility it is better to use different format, for example: A1-C2, B1-D2, C1-B2, D1-A2. This guarantees that two players can meet each other in the second time only in "grand finale".