I want to share my ling wind findings and see if anyone else has to same experience.
I own a H2 15 which I felt was not great in light wind when using line extensions (3m). The steering lines were always slack. And as soon as some tension was added, the kite would stall.
My assumption was that the drag on the line was enough to cause the kite to almost stall when the wind was light (+/- 8 to 11 kt range). I fixed this by moving the steering lines forward (more bar pressure). With this new setting, I can have some tension of the steering lines without going into a stall. And the kite feels/reacts a lot better!
In addition, I checked the lines and found out that the front line stretched quite a bit (only with the bar with the extensions). I fixed that as well (back to equal length) and can fly the quite with full power setting (which gives me a better range). Unfortunately, if there is any more stretch, I am stuck as I am on the last knot (at the bar).