The PPQ Classic (lever magazine release) has been legal for IDPA for some time. I was told by a Walther official that the approval of the M2 (button magazine release) was obtained for IDPA. Under the old IDPA rule book, the PPQ was an ESP pistol. It is an SSP pistol under the new rule book.
The PPQ Classic (paddle magazine release) is on the approved list for Production in USPSA. Neither the PPQ M2 4 inch nor the PPQ M2 5 inch (button magazine release) are legal for Production despite numerous requests to Walther to get the M2's added to the approved list for Production.