I think they have a tendency to Hindenburg in light winds and depending on the aspect ratio can overfly. Look at the new f one, not so much delta shape, longer wingtips I think to balance the weight more backwards and to improve turning. It looks more like it's predecessor ( can't remember name ).

I think the only good features are the grunt and the easy relaunch.

Cheers
Rich

Hey I used to ride a slingshot bow for a few years, and this year went for a 9m B3.

I notice a huge difference in the delta, it's true it has bugger all low end. I'm 85kg and i can get out in 15kts with it, just. But as soon as it gusts up a little and we start to get some speed HOLY CRAP!!! The top end turns on really fast, I don't ever remember the standard bows doing that they were always a bit more predictable.
Anyway i didn't like it at first, and it took me a few rides to get used to it. Felt like I was learning to kite all over again. The power comes from a different part of the window because it flys so far forward (maybe because of the delta? not sure) In the low end you have to turn it a bit and send it through the middle to pump up the speed. But i'll never go back now. As soon as you get used to how they fly it's amazing what you can get out of these things. The power at the top end comes on hard and fast and is very useble

85kg on a 9m in 15 knots that sounds about right. What do you expect from 9m? If you want a low wind kite at that weight get an 11m or bigger.