You haven't mentioned anything about your size, but it really doesn't matter, you'll do a lot of looking to find a boat that is a better all around boat than the Gulfstream. It sounds to me like you need a lot more time in the saddle.
The Gulfstream and it's poly sister (Sirocco) are magnificent boats that are capable of just about anything. The initial stability might feel a little shy at first, but no more so than most sea kayaks of its type. With more experience, you will begin to appreciate the way this boat deals with bumpy water. With a lot of experience, you will love the boat.