The more current, the more torque, or in other words, the more advantage the motor has against external resistance such as weight and roll resistance (to keep it simple). So as current increases the less those two things matter during acceleration. Too much current will with lots of weight and little roll resistance = wheel spin. Lots of current with little weight and lots of traction = quick acceleration ...if the CG is low enough. Otherwise it will flip. so limiting the current will help prevent wheelspin when traction is low and will prevent the front end from being too light when traction is high.

Will it effect speed? Top end....let's just say that it doesn't stop the motor from reaching full RPM. It mostly acceleration. It takes way more current to make the truggy change speeds than it does to make it maintain speed. In fuel speak, this is why city mileage on a typical regular fuel passenger vehicle is lower for stop-n-go city driving than on a long highway trips.

Not according to their advertisements nor the manual. I haven't tried to adjust it further than 7 to see if it would go that far. I just bought a 2273 from the For Sale section. I should be able to squeeze .11/350 out that with 7V.