Far better car than your 92 960. The down side of the 95-98 960-S90's is more electrical problems can occur due to the electronics. The 24 valve I6 Engine is outstanding but again you have to follow the maintenance schedule this engine will not take neglect like the B230 would. The service writers and techs at my dealer all say the 96-98 960's were the best cars Volvo ever made. I have a 97 with 68K miles and absolutely love the car. The ride and handling is wonderful and the engine is so much smoother than my B230FT in my 87. I will tell you if she buys that 960 that you will be envious of her.
I've only seen a few problems with this car as others on the board. One expensive problem is wrinkles on the tops of the door panels. Your looking at close to $3000 ($600 per door panel plus labor)if you ever decided to have all 4 replaced at the dealer. One other problem is PNP switch on the transmission is a notorious problem. The other is oil seal leaks here and there. The engine and transmission should be filled with synthetic fluids for best performance.
Gas mileage is 16 to 18 mpg around town and 26 to 28 mpg highway.