I've used the Spring Creek kayak cart now for 2 summer seasons. For the start of the second season, I modified the cart by removing the single handle and adding two equal length bars, one to each side. Now the boat can sit with equal weight, centered between the two bars. With duct tape, bungies, etc., I got this to not only portage a 70# tandem plastic kayak but also a big aluminum canoe, and this is over some pretty tough trails!
This is truly the 4x4 of the kayak carts! Unlike other carts that have an axle, the Spring Creek has some serious ground clearance. Also the wheels work well, though I did have to add some washers to the mounting nut. This cart can straddle big rocks and small boulders in the trail where lesser carts would just get hung up. It's like a spider walking over a boulder field.
With my mods this makes out to be a good cart. I'd be happy to share pics and more notes about this with anyone wanting to know more. I'd give it a 10 if spring creek would include these mods but as it is just an 8.