9 weeks is ideal
"I just wonder, if you guyz would be given a choice between 200 mg of primo for 9 weeks or 300mg for 6, which one would you choose?"
6 weeks is a bit short for Primo, so 9 weeks at 20 mgr/week.
There will be no more results after 9-10 weeks anyway. Unless you up the dose. So best is to stop after 9 weeks.