Yes you are right, using a strafe button helps slightly at low speeds. at higher speeds any use of strafe buttons will hinder the speed gaining or even slow down. With low speeds i mean speeds below 550 units.
You can enable a primitive speed display (3.0 might have something better

If you jump normally your first jump gives a speed of 459 units, the second around 518, the third 577 units.. When you press jump and a strafe button you can reach up to 520 units on first jump. That jump on toxic seems to be the only jump doable like this. The gaps on darkzone are too big. An other way to gain (a bit more) speed is to jump, release forward, press a strafe button and move your mouse in the same direction. This makes a kinda curl jump as you have high control about your 'flight path'. I have been able to get up to 580 speed with such a jump. However as that jump makes you change your direction the jump it self will not get you FAR but gain speed. It can be used to bet enough speed to cross the gaps on darkzone with the second jump.
Now remember i said that from certain speeds upwards those two will not make you gain more speed just a normal jump will do that. You can try this on silvercity. Use one of those two jumps to start and jump from one corner to the opposite corner, You will hit the other corner with around 1000 units per second depending on how you started. I have not been able to get over 700 units when using those strafe methods only a normal jump will.