wind speed, heavy sea.. boat speed EDEL 4

Sailing in Adriatic on Bura wind (northeastern wind), in pretty high seas with only main sail, slightly downwind i noticed that my edel 4 tends to turn a lot into the wind when the wave hits the back of the boat. Waves, since we were going a bit downwind came from left side, slightly from back (say from 7-8 o’clock) and turned my edel 4 pretty much to the left, into the wind….
So I wanted to ask what is the strongest wind that you have sailed your edel 4 (with retractable keel) and with what sail? IO have roll genoa and main sail, and last weekend we sailed only with main sail. Would it be better to sail with half rolled genoa?

How much wind and sea can Edel 4 take?
what is your top speed? later that day on western wind (maestral) we did (by gps) some 6.5 knots comfortably…