Actually the standard 997 had an M96 until they went to the 9A1 in the 997.2. The M97 was in the 987 and 997S. They are supposedly very similar internally including the improved IMS bearing design. The 9A1 has no IMS bearing to fail, but I believe it does have some issues with carbon build up in the DFI motors.
Here are engine models vs Porsche models, look at page 9 for the M96 in the 997.
https://dl.dropboxusercontent.com/u/93289189/Porsche_Engine_Codes_1952-2012.pdf