Yep, squally/frontal weather can be dangerous.
I went out last Sunday (1/8/2010) to Parham in SA and after a few minutes of kiting in sunny weather and 12kts of wind a cloud came and with it a 32kts squall. It was too late to land so I stayed about 300m away from the beach. About 10 minutes into the squall i stopped to do a careful turn and in that instant a massive gust came and ... IT RIPPED THE KITE OFF ME!!!
There was another kiter in the area about 250m from my position, but he wasn't affected by this big gust. He also managed to chase my kite down (after it landed back in the water some distance downwind from me). I don't want to speculate how strong this gust may have been, but just to illustrate what can happen this is a record I found from the same day from a wheather station on Lake Alexandrina near Milang in SA: