No reason to take precaution. The only one is the one I've stated, and even then it's incredibly low risk to transmit as you both have the virus and antibodies to it, in addition to oral HSV2 being rare (only 3% of all oral herpes infections). I never ever give it a second thought with my partner and I both have herpes.
Quite honestly, the doc's on the expert's forum are even less conservative than us - they would probably say no risk all around. Feel free to post there too if you have your doubts here.
Good news. So do you mean "absolutely NO reason to take percautions instead of the way you worded it "no reason NOT to take percautions".
Really no risk - you both already have it. Best to avoid oral sex when symptomatic, but then who would want to have sex during on outbreak, right? :-)
Otherwise absolutely no reason not to take precautions if you both definitely have it.