I purchased the R Strap by Blackrapid
about six months ago and have enjoyed using it so far. I didnt really like the default strap too much and was looking for an alternative. I saw that one of my friends was using it and he liked it and receommended it. At first, I was hesitant to spend $50 on a camera strap. There are also plenty of DIY tutorials online and you can easily buy parts to make it yourself for less than $15 but I figure spending $50 on something that will be holding $1000+ of equipment isnt too bad.
So far I have used it for general shooting, hikes, parties, and weddings and it seems to work well. I have been using it on my Canon 40D and now it is on my 5D. The ease of use when you need the camera is great because you can easily grab the camera and take a shot. I like how you can just let the camera dangle when you are not using it as it can actually take some load off from your hand because I had the tendency to always hold it with one hand. When you have the 70-200 mounted on the camera, however, the load can be a little heavy but havent had any issues with it.
The little pocket on the strap is also nice to store two extra compact flash memory cards. The only complaint I have is that the version that I purchased was an older one so the attachment to the camera was a little bigger so that you cant put the camera down as before when there was nothing mounted onto the bottom of the camera. Before, you can easily put down the camera with the bottom down, but now since there is a fastener on the bottom of the camera, I have to set it down on the side. It isnt a huge deal but it could have been better. Fortunately, I guess they realized this and came up with the FastenR-2, which is now included when you buy the R Strap, and with this new fastener, I think it solves that issue and might allow you to be able to set it down on the bottom. They sell the fastener separately, but I dont think I am willing to pay $12 to get it.
Overall, I would highly recommend the R Strap if anyone is looking for a better way of carrying their camera. It is great not having the camera dangle in front of me. It is quite convenient when you need it while also allowing the camera to be out of the way on the side when you dont need it. They also came out with a Double Strap for two bodies but I think I am fine with just one and might consider getting another one as opposed to getting the Double Strap. The Double Strap does look pretty cool though.