The sc6 is a better truck because it has better steering and is a lot more versatile (electronics lay out and rear/mid motor) The SC-R SP is still a great truck the sc6 is just an improved version.
How does the SC6 compare to TLR and AE short course truck in your opinion?
if you are running rear motor I would say they are very similar. The ability to run mid motor on a high bit track is where the sc6 really has the advantage.