Ice,
I live in the area and all three are decent estates in my opinion with varying pros and cons for each one:
Mount Eagle does have some through traffic alright but it depends where the house is; Also the residents and council have blocked off certain entry / exit points to restrict this happening – there is a fabulous green area, always with loads of kids playing around.
Fernleigh – you are spot on about what you said. There is a house for sale in the estate been on the market since September and I would suspect its not shifting cos it will be looking out at the new 8 storey build you referred to. But it’s a nice quite estate and smallest of the 3.
Sandyford Hall is only busy at the entrance where the shops are, it doesn’t impact at all on the rest of the estate. There is the large green area at the front which is handy and a lot of cul-de-sacs which are handy for kids etc. There is no through traffic from the shops really which negatively impacts on the estate. It would be very handy to have shops, crèche etc within 2 mins walk.
All three will be within 5 mins walk of the luas extension which is due to be completed by 2010 which will be a huge plus for the area.
Anything more specific, please ask.