It does depend on how your going to use your ROT66. Most folks are wanting high output and not going to let the batteries run down below 3.6v or 3.7v so a high drain like the 30Q makes more sense.
In your case, you seem to be willing to sacrifice some of the high output in exchange for more run time at lower levels all the way down to lvp.
So in your case, the high capacity cells do make sense.
The cells you currently have should be fine. You won’t see a difference between 3500mah and 3600mah. The 36G may end up exactly the same as the GA.
Should you buy an untested cell like the 36G? Maybe, it’s Samsung so it should be quality. You can be the guinea pig and tell us how good they are and their measured capacity. Lol