I have the 8'6" by 30", 130l. 2014 model. It's brilliant. I honestly don't think i'll ever sell it!
I'm about 75kg, and use it predominantly in waves, but have used it a fair bit in the flat water. It's awesome in the waves, i can still bottom turn it like a surfboard, it feels agile and very stable, even in windy/rough seas.
As a comparison, I also have a 10' x 32" Alley Designs, which was my first board. The Allwave was the perfect step up for me - it is definately as stable as the 10", and feels much nicer, easier to manage and you can spin it around on a dime. It did seem a lot smaller at first - like I was paddling a shortboard - but you get used to that.
I'm sure it'll be a great first board. I'd highly recommend hitting some smaller waves once you are confident. You'll never go back