I am not particularly familiar with the exact percentage chances of transmission of HSV so I am not able to comment regarding the quote on percentages.
As you've suggested, the risk of transmission is much higher if you have active sores.
Suppressive therapy helps but does not completely eliminate the risk of transmission. The virus can be shed even when no sores are present.
I would always recommend using condoms. Even though there is no statistical difference between 1 and 2%, if the virus is passed on the odds don't matter in the end. Condoms have clearly been shown to reduce the risk of transmission.
Sorry I can't give you more specifics. I hope this helps some.