surveys highlight these differences and this information is shared with users and interested regulators.
To the extent there is systemic risk in the model itself, this lies within the control of the regulator and the principles set down within the regulatory regime. Asking many firms to implement model X (instead of a very small number) does not remove the risk.
The exposure of firms to the operational risk of simultaneous software failure at a point in time does exist, but we make considerable effort to manage it to a minimum through robust software development, testing and release procedures. We are (and have always been) willing to expose these processes to model users.
If such systemic risk does exist, it should be the concern of the system regulator not individual firms (because individual firms are not in a position to manage it).