The Straight Ramps' effectiveness in Stunt Run events is about the same as Curved Ramps. They are slightly less useful, however, because due to the smaller inclination, they do not give the player as much Air Time as Curved Ramps do.
In other events like Race and Road Rage, Straight Ramps can become very useful. Although they are not as inclined as Curved Ramps, they still provide enough inclination to propel the player's vehicle into the air well enough to perform a vertical takedown. In certain situations where the opponents are closer to the player, Straight Ramps' loss of inclination in relation to Curved Ramps actually helps the player. The less Air Time allows the player to come back down more quickly and gives him/her a better chance of connecting without letting the opponent escape.