I'm not too familiar with the new BSG series, but I know a little of it's space battles, and FF outerspace sequences, like it's battles, are close in style (in fact, you can see the FF ship briefly in one BSG episode!), and they follow the rule of no sound in space.
BSG doesn't follow the 'no sounds in space' rule. Firefly does, much to its credit.
Sound is muffled, but not eliminated in BSG sequences. Sometimes I wish they just went all out and got rid of it, but I an understand the dramatic desire for sound in space. Worked to great effect in Firefly (and I was very disappointed to see it violated at the end of Serenity--I know it was explained, but said explanation didn't work for me).