VERY BAD IDEA.
Btw. my Agility has 14g rollers.
At 12.000 kms I put in 3x14g and 3x11 g rollers.
Yesterday, the rollers are changed because there was a big shudder and "delay" and vibrations.
The scoot has 19.000 kms.
Heavier rollers were completely torn while lighter ones were in good condition.
I have put again 3 lighter and 3 heavier, because I had them from the first pair of sets... but I do not think that mixing or chaning is a good idea, especially not three rollers instead of 6.