my honest answer is to keep it all as simple as possible at first. Buy a commercial controller that plugs into the receiver and get a robot chassis running.

Many people over the years have tried and many have failed to develop their own speedos. A few have succeeded. One thing that all had in common was a great expertise in electronic design.

Even with the heavyweight I won robot wars with, typhoon 2 we had some custom electronics in there to help with the disc spin up in the later variations of the machine and those were no easy feat to develop.

I can understand your enthusiasm but you will save time, money and many a heartache on your first machine if you buy a ready made controller, ie plug and play.

The sabretooth is a nice controller but it's rated specs are somewhat high. Personally I have burned a few out using them to their limits with overvolted drill motors.