I went all in and bought a Z8 thinking it would bring the the A9's fast, silent and blackout free use together with the D750's F-mount lenses and flashes. However I've ended up using my damaged D750 mostly over Christmas the Z8 can't used the AF assist light on the flash so it really struggles to get focus at all usually missing the shot if it does eventually focus and often not getting focus lock. The D750 in the meantime can lock focus almost immediately since it can use the AF assist light.
I'm unsure what to do now and kicking myself for not just grabbing a good condition D750 that was for sale here recently as it seems it's always going to be better for flash use. I've been looking through ebay listings but the condition and pricing is extremely variable with people having a very different idea of 'very good' or 'excellent' condition to me, getting up to the good condition cameras seems too much money for an older
second hand camera.