I have been flying my Ventus (Lenger) for about one year now. I have both wingtips, 5m and 6m and behaviour is very good.
The retract, which is done in aluminium plate (not the tube one seen here) had severe problems as it did not block when extended. I had to do new parts here so as to allow getting an angle greater than 90º between driving shaft and leg slot. Now it works fine.
I had the opportunity to compare it to a LET Ventus, this one also a fantastic model, but weighing one Kg more tan the HF one.
Here is a photo of the first flight on the slope, with 5m span.
Here is the 6m version on a tow day...