I've been a fan of the Black Rapid RS-7 for several years and have used it on my main body constantly. The only time it comes off is to put the camera on the tripod. My camera is a heavy beast (not mentioning brands, I can do without the I love you and I hate you brand comments) and needs to be well supported. Manufacturer neck straps suck, that's as simple as it gets, they suck. They're a pain in the neck.
The RS-7 fit the bill very well in that it supported the weight nicely over the shoulder and kept the camera in the convenient "holster" position like an old American West gunslinger ready to grab and shoot.
The one bug bear I had with the strap was that it would sometimes move around on your shoulder, particularly when climbing or wriggling through awkward spaces. The kind you often find when exploring our urban environment. Occasionally that big black beast would land in the awkward place, you know the one, the spot where when it happens at the theater every male crosses his legs and hisses in a breath and every female smiles and giggles.
The difference? The Sport has a "Brad" strap which helps the whole rig stay put no matter what you climb in or out of. Magic. Once adjusted for my body shape the strap just disappeared and well managed the weight of the camera. Like its bigger brother the RS-7 it amply handles the load and distributes the camera weight across the shoulder evenly. No more camera smack in the...
You can find more information about the Black Rapid Sport Slim on BR's website.
Distributed in Australia by Adeal the strap is available in many camera shops around Melbourne. If you're tired of the pain in the neck, then take one for a test drive.