I have read everything that has been posted, and would like to add that I visit this place regular and have found no ill affects when visiting, in fact quiete the contrary... I find the energy there is very warm and welcoming, not at all malicious, I leave with a renewed sense of wellbeing.
This place must have held some significance at some time as there are also remains of two stone cairns further accross the mountain and I have read that there is a possibility of a burial chamber just over from the ring cairn.
I would also be interested in finding more information about this site, if anyone has any.