I haven't seen one my self but i went to this place (korangvale i think) one day and i heard the grown ups talking about this black cat they had seen and then they told us and it was a fairly poorish area and i don't think they had internet or anything. so if it is a myth how could have these people have known if they dont have internet(im guessing cause they were pretty poor) or anything to find it out.
and i think its kinda cool if there is big cats. maybe in 20 years time we could be keeping a big cat under our wildlife licence