Top witnesses and exchanges are being recommended to continue to use the non-MIRA version for now which has the same replay performance as before (several hours if using a high end CPU with enough memory).

Lower-ranked witnesses may prefer to take the hit on replay time in order to get the better low-memory performance of MIRA and lower deployment costs. Likewise for API full nodes.

The developers plan to circle back and make additional improvements to MIRA making it more suitable for all uses, but not until after the SMT release.