Do they have a rotor rpm gauge?
Is there an audio warning if the rpm deteriorates?
Mine has a rotor rpm display so I can teach people to takeoff.
Takeoff is the only time it matters.
In mine because I have a weak pre-rotator (a car starter) I start with the cyclic full forward so the blades won’t hit anything as they get up to speed. As I am rolling out to the centerline I bring the cyclic half back at 100 rotor rpm and full back at 120 rotor rpm. I advance the throttle at 180 rotor rpm. She typically lifts off at 290 rotor rpm and flies at about 330 depending on weight and conditions.
After takeoff the rotor rpm manages itself so there is no reason for a warning.
Some people fly without a rotor tachometer and just use the look of the blades during the takeoff procedure.
The gyroplanes with more powerful pre-rotators run the rotor rpm up to 200 rotor rpm with the brakes on and come full back with the cyclic and go to full throttle almost immediately making it somewhat more fool resistant.
More weight, more Gs or more altitude will speed up the rotor.
There is a slight increase in rotor speed as the airspeed picks up.
I cannot unload the rotor enough for long enough to cause an unsafe low rotor rpm in any gyroplane I have flown.
Helicopters have a very narrow rotor rpm range and that leads people to imagine that it can be a problem on gyroplanes.
On takeoff if I go too fast for the rotor rpm I can stall a blade and run it into the tail. I can feel it tapping in the cyclic first and all I have to do is to get the cyclic forward and slow down and start over.
Sometimes fixed wing pilots forget about the rotor when doing stop and goes and center the stick as they advance the throttle leading to the rotor slowing down as the aircraft speeds up. When they remember and bring the disk back going fast it can cause problems.