Sure, amps x volts = watts. Watts = power. You need a certain amount of power to get these buggies going. When you decrease the voltage, you increase the amp draw to get the same power. Amps create heat and stress the electronics.

This is why 2s packs get killed and puff so often in 4x4 SC trucks with 4600kv motors. This is also why people sometimes run 6s in buggies and truggies with slower (~1400kv) motors. The total speed is roughly the same, but the higher voltage will deliver the power more efficiently.

So if there is a choice between 3s and 4s, go 4s. If you're looking at a 3s/5000 for example, a 4s/4000 will be roughly the same size and weight so you don't lose anything there either. But you'll have more punch and better run time with the same total power.