It seems also plausible that the cases where paternal mtDNA are passed on, would be disproportionately likely to have mitochondrial disease and thus eventually

It seems also plausible that the cases where paternal mtDNA are passed on, would be disproportionately likely to have mitochondrial disease and thus eventually die out. We don't know that this is so, but it seems more likely true than not, given what we do know. If so, they would not really impact research done over evolutionary timescales.