First Review so please let me know if I've missed anything....
Bought the Carry Speed shoulder strap about a few weeks ago and got to take it out for a good run the other night. Originally I was looking at the Black Rapids, but at over $100 down here plus extra for the attachment to connect it to a tripod without having to stuff around with it, the Carry Speed at $38 including delivery was looking the goods. It took under a week to arrive, which is pretty good (US to AUS), and was bought off Ebay
One complaint - it didn't come with instructions, though was well packed. Anyone with a few brains could work out how to put it on within 10 minutes I guess... I took about 20 having said that, it was reasonably simple to install, and I simply was trying different ways to fit the thing.
The strap fits comfortably on my shoulder, and although I am no giant, I guess it would fit on most people with no problems, as there was plenty of extra strap left to lengthen the thing, which tucked nicely into the shoulder cover. The under the arm strap is a good thing, keeping the Carry Speed quite steady, even when maneuvering through crowds, the camera was firmly on my hip. This was without the "Uni Strap" connected to my belt which is another accessory included designed to stop your camera swinging in front of you when you bend over, and it is also a safety catch in case you forget to tighten the "carbine" clip properly.
On the night we were at a night market in Melbourne, which was jam packed with thousands of people (pics coming) as it was a hot evening and a great atmosphere. Even so, after 3 hours I was still comfortable with it on, even though a lot of the night seemed to be spend dodging people - the camera was never in the way. Afterwards we went for a stroll down the beach for an hour or two, still carrying the camera and still no fatigue.
In summary - I highly recommend the Carry Speed. At around a hundred dollars cheaper than the Black Rapids (at least for Aussies when you take into account the extra postage, plus the tripod adapter on the BR). FWIW I did find some BR's in a camera shop a while back, and quality seems comparable.