I was fortunate enough to obtain an Expedition LV from Seabird Designs before the release here in the United States to use in the SD Kayak Challenge.
The quality of the kayak is far superior to those at the same price point offered by other manufacturers. The front and rear storage hatch covers are incredibly durable and fit extremely well. The wind was kicking waves reaching 1 foot and boats racing around were creating wakes reaching 2-3 feet and despite the water heavily splashing across the kayak, no water whatsoever entered any hatch, including the small hatch with a twist down lid for a cell phone, wallet, keys, etc.
In regards to stability....this model does wobble a little as you first enter the kayak as other models do but even sitting in place on the open water, it would take quite a bit for someone my size to capsize the kayak. (I am 5'6" tall and 130 lbs). While paddling, the stability increases and glides across waves very smoothly whether approaching head on or from the side.
The rudder included with the kayak makes this kayak an incredible value considering it is priced more competitively than other kayaks at the 12' length. The rudder system is very simple to operate and is very responsive. Very little pressure applied to the left or right pedal really helps keep the kayak on track over long distances. Fully depressing one of the pedals makes turning around very simply eliminating the need to back paddle as you would have to do with other models of this length.
I went out to the lake after work so time was limited before the sun went down. If your purchasing the kayak and heading straight to the lake or river, take a screwdriver along to adjust the braces otherwise adjusting the seat and foot braces/pedals is very simple whether at the dock or out on the water. Once everything was adjusted, I spent over 3 hours out on the water and experienced no discomfort whatsoever. Even after paddling approximately 15 miles, carrying the 55lb kayak from the water back to the truck was very easy with how well the weight is balanced.
I will be taking the kayak out on the river the next chance I get to go out pending the weather and I will provide another update with how it handles on the river.