I bought the BlackRapid DR-1 Double Strap in order to safely carry and use two camera bodies & associated lense while shooting off the back of a moto during a stage race. My goal was to be able to focus on the shooting and not keeping the cameras from slipping off my shoulders - especially during the rain which we had for a few stages. Goal was met, and the double straps worked great with female anatomy. I could easily use my DSLRs from either side and could also easily get on/off the moto.

I also used the double strap while walking for the time trial day and everything was still comfortable.

Like all photographers, I have to carry more than my DSLRs which means that I needed to also use a belt with pouches, which sometimes made the balancing the heavier camera with lense (70-200mm) tricky with heavier component on my belt. I also purchased the Joey 3 pouch to carry my phone and recorder but I found that it didn't carry as much as I expected - ended up putting the recorder in a pouch on the belt.

While expensive, the straps are worth it when making sure that cameras are safely attached. They also somewhat evenly distributed the weight even with a heavier (bigger lense) on one side.

I bought the double strap for running around convention hall floors. I generally carry two cameras when working an auto show - my main camera with a 12-60mm lens and a second body with a longer zoom. Carrying two cameras on my shoulders using traditional straps cause my shoulders to tense up and I end up with awful upper back and neck pain. I'm also generously endowed, so if I cross the straps across my chest, well, it draws unwanted wide-eyed attention. This system takes away the "cross your heart" effect and distributes the weight across my shoulders more evenly, and I don't tense up and have the resulting stiff neck. It's also solidly strapped on you, so in other situations, e.g. walking around outside with your camera, it's harder for someone to come along and steal it off your shoulder.

While I can adjust the length of the straps, the cameras can get a bit bouncy while walking. If I decide to use only one camera, I haven't figured out a way to secure the empty strap, and it pulls a bit without the counter-weight. It's also more expensive than some camera bags, let go of my arm!

The system, while expensive, is a comfortable way to carry two cameras around with the confidence they won't slip off your shoulders. (Note price below: I made my purchase several years ago.)