I recently purchased a sled and dragging vest from Christian's Fitness Factory. While I have not yet been able to use the sled, I have been using the vest.
CFF Dragging Harness
What does it come with? The harness also comes with a dragging line for a sled of any kind.
The dragging line is a bit annoying, because the carabiners don't sit longways with the end of the line, but sideways. This means the lines don't pull smoothly forward and backward - you can see it in the illustration of the drag line on the harness's page. This doesn't seem to affect pulling performance but it seems lie it would eventually impact the longevity of the carabiners.
How does it fit? It goes on easily. The (plastic) buckle adjusts easily but grabs tight, and the straps stay where you put them. The padded shoulder portions are comfortable and wide, and distribute weight well when it's buckled properly.
If you buckle it a bit too tight, you'll feel most of the weight from the dragged object in your abs and chest. It's uncomfortable with the buckle pressing down on your chest. However, if you adjust it more loosely, the weight rides properly on your chest and shoulders.
It is also easy to put on and take off, even on a client with a shoulder/arm injury, which means it's easy to superset in sled drags instead of just "set up, do these, move on to the next thing." This is a very good thing when using the harness as a training tool for more than one person, too - I can easily use one vest with two clients and swap it back and forth with a one-buckle adjustment. This is much faster than a weight belt with a tow strap fed through it.
Quality: 4 out of 5. On the Ironmind-like you-can-use-this-to-drag-a-plane-is-a-5 scale, this isn't the best it could be. But it's very solid, and it seems to be holding up to heavy use so far. The weave and construction are good, too, and none of the parts seem cheap or poorly made. It's well made.
Overall: If you need an inexpensive harness, this is a good one.