I got the chance to use the Carry Speed sling at a Harvest Fair on Saturday. I have to say that I am a convert, the sling is way more comfortable and functional than a neck strap. Once adjusted the camera with a 50mm 1.4 lens laid in place against my upper hip. Grabbing it for a shot was quick and smooth.
The Carry Speed has a quick adjustment feature which until now I didn't know what I was going to use it for. I found it useful when sitting, a tug on the front adjustment ring and the sling shortened enough so that my camera was not touching the bleacher seats....turns out this was very useful.
The neoprene neck piece stayed in place front to back but would occasionally creep up to my neck. I wonder if the thicker Pro strap would have done the same thing.
All and all I am very happy with the purchase.
D600, D90 w/MB-D80 FX Sigma 20mm f/1.8; Sigma 35mm f/1.4; Sigma 50mm f/1.4; Sigma 150mm f/2.8; Sigma 70-300mm f/4-5.6 APO; Nikon 300mm f/4 DX Sigma 10-20mm f/4-5.6; Sigma 30mm f/1.4; Nikkor 40mm f/2.8; Sigma 18-200 f/3.5-6.3; Sigma 2x TC; Kenko 1.4x TC; SB800; Giottos MT-9360 Tripod with Giottos MH-1300 Pro Series II head