Hey luismx, I think that the 6'4 will be great mate. I predict all that will happen is that you will get a heap more waves and hence enjoy your surfing even more. The Dom is a great shape, very versatile, you will be stoked with it. I have a 6'8 which is prob way too big for me (I'm a very similar size to you) but I got it cheap and I find it HEAPS of fun to ride in all kinds of waves. I would def go smaller if I got a new one but prob only to a 6'6. Enjoy it mate.