The plain and simple is this:
27MHZ is a general use band. This means that it can have anything from airplanes to robots. It's also the best for submarine use due to the longer wavelength of the signal. Since the signal is also generic, frequency conflicts are possible with others using the same channel
75MHz is surface only and, if you go FM or PCM, has little to no glitching. Again, the signal is generic so frequency conflicts are possible with others using the same channel
2.4GHz is a general use band but, unlike the 27 and 75 bands, the transmitter and receiver are linked so that the receiver only responds to one transmitter. The biggest advantage of this band is you don't have to have an antenna sticking up like on the other two. The antenna can be hidden inside a boat's cowl or left in the radio box itself. The problem with this band is due to the short wavelength, the signal can be reflected by the water's surface.
As far as responce, there isn't enough difference for you to tell. It's like using a servo, some take 1.5 seconds to go full "stop to stop" while others will take 2. I don't know anyone that can sense a .5 second difference in speed