The Javelin is a ICF rules Olympic style K1 racer. It could be described as a intermediate, or stable marathon boat. Unlike many trainers, the hull is rounded and not flat. This makes the stability somewhere midway between something like a Laser, and the top sprint boats. Maybe a 3.5 (with top sprint boats at 1).
It is an old design, but still one of the most stable and predictable ones out there. It is obviously a bit slower than the full on sprint boats, but a world more stable and relaxing to paddle. It is relatively low volume, with a low deck. So, you need a skirt to stay dry if you are in chop or a fast river. At 185lbs, I sank the boat enough to put up a rooster tail from the submerged overstern rudder at full sprint. I think it is rated for under 160 lbs. But I still borrow the boat at times for low water. Its stability makes it a great river boat. The low deck is very tight on size 10.5 feet. At 6'1" I have the seat all the way back, and it is tight.
As for build, the one I had was well over 20 yrs old in Kevlar with significant sun damage. A new cover of paint on the deck, and clear resin on the hull, and the boat is like new. They are hard to kill. The hull flexes easily when run over rocks (wonder how I know that?). This boat had many many miles on it. It weighed in at some 22lbs or so. I give it a ten because it has lasted over twenty years and is still going strong.