We have one Ullman on our Ribcraft Mitigator and like it so much we are adding 2 more and one on our 30 foot Nautica.
Not only have we found it to be great in heavy seas but to our surprise very comfortable on long calm trips as well.

We often have tows lasting over 10 hours and spend 1/3 of that time at speed and 2/3 traveling slow while under tow. I originally thought the seat was going to be uncomfortable at the slow speeds but was amazed after having spent 12 hours on it one day. It not only absorbs shock but also keeps you in an ergonomically correct position at all times. Most important of all, it takes care of you when you hit the unexpected wave and aren’t ready for it