I read that the SCN6 will take a heavier load, but is slower than the SCN5, which takes a lighter load.
Be aware that no matter what motor/actuator you decide to use, the speed will always be affected negatively when you
apply load (torque) to it. The speeds listed in these spec sheets are given with NO load. Each solution will vary by how much based on what you decide to use for motion and the design and weight of your sim. This is where engineering, math, and some trial and error comes into effect.
The SCN5 is better suited towards moving a seat like I use at a great rate of speed because of small amount of load(torque) applied to the actuator during movement. I did attempt to move the pedals and steering wheel all together during a trial when I first started, and I was not pleased with the results. These actuators have weaker pull force than push force. So when shifting larger weight, by having to pull it back, was really straining hard to do so. The speed was decreased dramatically, and I feared that continued use would eventually cause damage to the actuators. So I stayed with the seat mover setup I use now.
The SCN6 would be a better option for moving more weight. But the cost will go up as well.
Spec Sheet for SCN6http://www.miraiintertech.com/home/downloads/SCN6.pdf
You have to make sure that you balance your sim in order to keep your load on actuators within limits of operation for the
model you choose to use. There is no 'easy' answer on how to calculate this. This is where you come in with trial and error, and problem solving through your engineering/construction skills.
Just things to keep in mind when choosing your design and motion system.
It's a very exciting and satisfying feeling once you complete your project and have it working just the way you want it.