Turbine powered models are often equipped with governors limiting their top speed to the 200~250 mph range. Many high powered turbine models are capable of flying faster than the airframe could sustain. Eventually they would simply rip apart in air without a governor and/or sensible throttle management preventing such an occurance.

Hotline gliders, on the other hand, are vastly lighter weight and are able to achieve staggeringly fast speeds only during precise atmospheric conditions. Their much higher strength-to-weight ratios (made up term?) allow near 400 mph bursts during dynamic soaring.