From an engineering-style control perspective, closed-loop is better than open-loop. There are many degrees of open and closed loop but the Su-25T system is broadly open loop. The HUD tells you left or right and right and wrong but it does't tell you how much left or right, or how right or wrong you are, so the drive cannot be proportioned to the error. As such, from a purely analytical perspective, the drive will tend to lead to more overshoot and/or a slower response time.