One difference between 1:1 and our equipment is the prime mover RPM. Diesel engines have a very narrow power band and low max RPM, requiring multi-gears to match available power/torque and road speed. Our electric motors have a considerably wider RPM range, depending on turns, etc. I chose a low RPM 85t motor for my Payhauler. It turns 5200 RPM at 7.4V, so is about double the diesel engine RPM in the real truck. By using a 3-spd trans, I just about replicate prototypical road speed, since the 1:1 had a 6-spd trans. Lower turn motors spin a lot more RPM, reducing the actual need for a many-gear trans - use of one speed or a 2-spd trans works just fine since we seldom see anything like scale speed (70 MPH) with our trucks.
But then, nothing beats shiftin' those cogs 9 times going across the room! To each his own - just have fun doin' it.
Ken