It is not based on ki, why? because
JOB ( a user ) Commented on this post:http://www.animevice.com/forums/battles/33/thor-vs-gokuvegetagohan/332113/?page=12
That Namek saga GOKU traveled the namekian planet in 0.5 seconds, then does the VIDEO above show gohan SSJ2 Traveling planet SPEED to you??? not to mention gohan SSJ2 is a few hundreds of thousands times stronger than Namekian Goku.