4s vs 5s and gearing

OK i,ve look for the Flightpower 4350mAh, 5s. The weight is about the same, and i,ve try a 14T pinion and i,am to the limit but i can use it. On BrianG speed calculator, with my actual setup i,ve a top speed of 40mph, and if i go with 5s and 14T pinion, i have 46mph.
Do you think that i,ll see a big difference with this gearing and a 5s, and for the runtime and temps, i think it should be about the same

What do you think