I doubt if larger stores would open near Swinford. Swinford/Foxford have a long tradition of shopping in Castlebar and Ballina. The remainder is picked up by the small local stores. So a large store would have to purchase land/get permission to setup a store. Then only take a share of the local trade. Local stores would object strongly to a local store setting up.
As regards property investment, property in Foxford is moving extremely slowly, there is a large amount of property for sale. Swinford would not have as much oversupply.
Not sure any of them a red hot investment.