Yes, it is a great resource. It is nice to have those old recordings preserved and available.
His influence in a living one, though. His granddaughter Molly Waters and great-granddaughter Mary Shipley are at the West Virginia Folk Festival http://www.wvstatefolkfestival.org/ffschedule.html
every year, continuing his work. Mary Shipley was born long after Dr. Gainer had died (she's about 18), but she has learned many of the old songs from her mother and other relatives.