Shifting the recurrence over by one and adding, we have: \[\begin{aligned} x_n &= x_{n-1} - x_{n-2} + x_{n-3} - x_{n-4} \\ x_{n-1} &= x_{n-2} - x_{n-3} + x_{n-4} - x_{n-5} \\ \implies x_n + x_{n-1} &= x_{n-1} - x_{n-5} \end{aligned}\]so $ x_n = -x_{n-5} $ for all $ n $. In particular, $ x_n = -x_{n-5} = -(-x_{n-10}) = x_{n-10}, $ so the sequence repeats with period $ 10 $. Thus, \[\begin{aligned} x_{531} + x_{753} + x_{975} &= x_1 + x_3 + x_5 \\ &= x_1 + x_3 + (x_4-x_3+x_2-x_1) \\ &= x_2 + x_4 \\ &= 375 + 523 = \boxed{898}.\end{aligned}\]