Rob, I have an Ultra 35 and it bits well the SM2000 and, so far has worked very well in 35+ kn winds for two years.
I bought the Ultra at the Newport, Road Island boat show the week after I had a scary drag incident in Province Town (Cape Cod) using the SQR anchor that came with Ipanema and have worked well for 10 years.
I have sailed overnight from Boston and set the Danford well in at 3 AM before going to bed. Wind was light from the north but I made sure it was well set. However, in the morning the wind shifted to the east with a strong 30 kt breeze and next time I checked, I was rapidly moving towards the beach. I turned the engine on and brought the anchor up noticing that it was fouled with a fishing net. Unfortunately, the prop ended up being fouled by the line attached to the fishing net, but fortunately I had already removed the net from the anchor and I sent it back on time.
Thinking about the incident I realized that, although the anchor had set well the night before, the 90+degrees wind shift had pulled the anchor free allowing it to catch the net before it had a chance to set again.
Back to Newport boat show, Ultra had demonstration sand and gravel pits to show the effectiveness of several models of different types of anchors. As a scientists I used to be, I asked if I could do a test to evaluate what happened with the CQR and the Ultra well set when the wind shifted 90 degrees. The result was clear and reproducible. The Ultra remained set and just rotated digging itself more, while the Danford came out and took a while before it set up again.
As I kept repeating the experiment (Scientist don’t believe a single finding), more and more people joined the spectators to the point that they ended up selling several anchors that afternoon and were willing to give me a discount above that of the boat show when I bought my anchor.
From this experiment it was clear that one of the great advantages of the Ultra anchor is its ability to remain well set when the wind shifts. I believe this is due to the winglets it has which guides the digging. The other reason may be that the tip of the anchor is weighted (filled with lead) which helps it to dig into the bottom. Finally, compared with the Rocna type anchors, the Ultra has much greater area opposing it dragging motion which should give it an advantage on soft mud bottoms.
Ipanema SM2K 278