Differences between EV3 Gyro and Hitechnic Gyro
IMO there are no advantages of the old Hitech gyro:
The most fundamental difference is that the Hitechnic Gyro is a analog (ADC) device while the EV3 Gyro is digital (serial). This makes the Hitechnic Gyro badly suffer from drift and oscillating offsets (both at stand still and by changing output voltages caused by electricity consumers such as motors switched on/off) which has to be filtered off. Digital sensors like the new Lego gyro are not affected by these interferences - basically - at all.