They won't change because of any MIMIC stuff because MIMIC is not applicable to theoretical models. MIMIC corrects a theoretical model based on measurements of an actual amp. Since there is no actual amp the model will be unchanged.
However... there has been a host of changes to the underlying modeling so the FAS models will sound and feel different but this will be for the better. For example, I just finished reworking the power supply modeling. It's now a virtual AC supply (by default, can be set back to DC if desired) and I'm sitting here stunned at the difference this makes. Literally stunned almost to the point of speechless. I always felt that AC supplies were a compromise and if it were cost-effective, manufacturers would use DC supplies so I used a DC supply model in the prior firmware.