For me, the 45MP and CFExpress slot were very important and after spending half a year without an R5, I still stand by that. The R8 gets me all the shots I want, but I routinely run into the buffer limits and 24MP doesn't allow for extensive cropping.
With Sigma now doing APS-C lenses, I could imagine trading the R5II for a future R7, but that's at least 5 years into the future, something for when both kids are finished with primary school
ES+flash is, I suspect, the last technical feature that can really improve my style of shooting. Everything else is just GAS!