The events are quite similar as far as anaerobic and aerobic demands; however, the mindset is the biggest challenge. Harold Schmidt did the best job as he ran sub 47.5 and sub 1:45. A few others showed sub 1:590 all the way to sub 1:47 and was world class hurdlers but I'm sure some of them just hated the 809m or feared to fully attack it like the did their ONE lap hurdles speciality.