The booster is for the ground launch I think but it wasn't included at IDEX 2021, it helps the missile get to altitude and the speed for turbojet to function and the rocket motor falls off. It doesn't effect range, the turbojet is the propulsion that will take it to those far ranges.One picture has a booster.. so if its 250 KM range, that means the missile range without the booster is 150 to 200 KM..OR. if 250 KM range without the booster, that will mean 350 KM with the booster,,
Still a lil' confusing isn't it?
The missile traveling at 5 meters will give a very short time to react to ships considering the radar horizon rules, although with AWACS detection would be greatly increased.
For example on the Type 45 the missile would be visible at 34 km away factoring in both radar height and missile height you would have 2 minutes to intercept the missile which is not as much time as you think especially when missiles are fired in large barrages.