Any analysis of appropriate minimum levels must recognise that, to be credible, they need to cover historically severe losses. Buffers need to be sufficiently high to withstand sector wide stress while remaining above a credible minimum. The calibration needs to be set at a level that is appropriate to promoting long term stability.
Where there are tradeoffs, these should go in the direction of giving banks the time to reach the new standards instead of watering down the standards themselves. Failure to put in place high quality standards for the long term simply sets the system up for another banking crisis down the road.