Pure surfboards are the worst for light wind. Too much rocker makes them slow.
I had an F-One Bamboo Fish 5'4" and it is fantastic for light wind because it is very flat. It goes upwind almost as well as a raceboard. I was riding nothing else in all conditions while I had it. I lost mine

but I have ordered another one.

When well powered it does tend to skip out a bit but you can fix that by improving your technique.
If the Rocketfish is as flat as the F-One then it will be good.
I recently got an Airush Sector 60 freeride raceboard. It is proving to be huuuge fun. If you are into blasting around at great speed and like the challenge of carving turns on a wide board then I would recommend that.