It wont be a problem as long as she knows how to use both at the limit. I think it's a good idea to practice a emergency stop now and then in an open road, in different conditions to keep up the correct technique. My 83' 242 Turbo can outbrake many cars (stock brakes), beacuse the tires have such good traction (AA traction rated, Dunlop D60A2) and i can hold it at threshold before locking up. ABS is nice beacuse the car can be steered much easier during a stop, but in some conditions like gravel and snow, regualr brakes are sometimes better. As long as she is a confident driver, it should be ok. Learn threshold braking, and regular brakes will work just fine (don't just pump the brakes, keep em down firm until its about to skid, or skids shortly, then just let up a touch, and re apply.)