I did this last August and just came across this report I wrote at the time but never did anything with so thought I'd throw it on here in case anyone was interested.
I reckon that in similar condition and conditions a 12 hour round at Mullardoch is probably equivalent to a 15 hour Tranters Round. 8km shorter and about 1000m less climbing, similarly rough underfoot and as/more remote. They're really fantastic hills, it's probably a run I'll want to repeat sometime in better weather.