in the end, you get what you pay for...
my suggestion, save an extra $200 and buy a tributary tomcat tandem. not the 800lb capacity you're thinking of, but most good ik's aren't gonna come close to that.
i haven't heard the best things about sea eagle's ik's. kinda like the best boat that money can buy... at k-mart...
i'm 6'4, in the 280 range, and i use a tomcat solo. i absolutely love it. it can handle bigger stuff, but even with my fat ass it's still super agile in the technical stuff. best purchase i ever made!!
i have a hyside paddilac tandem for overnighters or taking passengers. it's an amazing boat, but i coulda bought 2 or 3 tomcat tandems for the same price.
any way you slice it, you're gonna have fun on a ducky!! keep your eyes open for a good used boat. you never know what you can find for cheap out there!! good luck!!