I interviewed for a (SRO)SSS-IT position late last year. I wasn't selected, but I'll let you know about my experience. I have no idea of your background, I was a Navy nuke. The POSS is pretty easy. It's all about speed, the concepts aren't too difficult to grasp. The ProfileXT is also fairly simple. It's similar to a psych exam. Most of the questions asked how you feel about something. The last part of the exam had a few problem solving questions, similar to what you would see on the math section of the POSS.
The area is nice and quiet. Nothing much in Waynesboro, but Augusta has plenty to offer. Savannah, Charleston, and Atlanta are close enough for a weekend getaway. Be prepared to lose your phone signal around the plant, most of us interviewing didn't have signal. I forgot already, but I think Sprint or Verizon is the only carrier with enough signal around that area.
Good Luck!