Did you consider the Sunova Surf 9'5? At your weight it would go well in surf and flat water. Weighs about 9.5kg in xxx construction.
Hi Tasilee, I am of a similar weight and get where you are coming from re weight of longer boards.
All of the boards in bold still have a lot of volume for your weight. I would have thought the 10' Nalu would still paddle well and the lower volume give greater control in the surf.
keep in mind to the longer the board the easier to snap/ crease they are particularly in smaller suckier waves.
You will find the GTW models lighter and stronger and they look great, have you looked at the 9'5 and 10 ft Mana's they surf well paddle well?
I think you have to decide whether you want to stay with the long board style and shape or progress to more of a surf shape.
If you go down the surf shape you will lose the paddle power and forgiveness but gain manoeuvrability
You don't want to drop too much in size and volume.
Something around 9.6'-10' and 130lt would be a good benchmark to start with.
At your weight you could go a lot smaller but too big a drop is a lot of work and commitment.
Having said that in a years time you might have to do the same upgrade again. (I know I did)
I have generally found the more expensive boards tend to have less weight for a similar size board in a given material and tend to be more refined.
Basically you get what you pay for.
Another brand to consider is the Imagine Impact 9.8 X 29 x 131Lt (a little expensive though. RRP $2599)
The Naish Nalu GTW is a great board. It was my first board and I still have it but it will be very similar to your current board, only a little lighter.
The JP Allround 10.6 is a good board but may be too close to your current board as well.
Sunova boards would be good.