I once spent 3 days on an 1990 Edel cat 35 in a force 8 with 10 to 13 ft waves.
We dropped sail, closed the hatches and locked the rotating mast. Dropped our 7 hp outboard and ran it on low revs to give us steerage, we pointed into the waves for comfort. Surprisingly our GPS made us making 1 kt over ground into the oncoming waves.
The motion was akin to driving a car over low hills, we only saw green water once during the whole voyage, and that was when we where surfing down a long wave/hill and met a short steep wave at the bottom of the curve. The water drained out off the cockpit almost immediatly.
Our autohelm was not up to the task of keeping us on track in the large swell, so we had to steer by hand the whole time during the storm. With only three crew this made for exhausting work.
Going forward on any boat in big waves is not my idea of fun, however this feels a lot safer on an Edel Cat 35 due to the wide walkways between the center cabin and the hulls.
After the initial shock over the size of the waves I felt very save during the whole voyage, the ride was comfortable and I was able to sleep without fear (While off watch, of course).
My father is 73 and still sails this boat single handedly from her berth in Crete, although he prefers to invite guests on board for company (So he says), but I think it's to help with the winches etc.
. Admittedly he is getting a little past it so sadly we will have to put the boat on the market soon.