Having had them in the boat for several months now, and having been out in all sorts of weather, I would never be without them again. In fact, I wouldn’t want to own the boat if they were suddenly outlawed!
The PH 20 is a fantastic boat, but it can be very susceptible to crew moving around the deck. The trim tabs enable you to correct for this very quickly and make it far less of a battle to stay on course. Wind-helm is also negated. Visibility is improved drastically.
The only warning I would give is that they do not remove the need for proper seamanship and caution. Set them too deep in a bit of a sea and you will come a cropper - for instance, if you let the bow dig in with the sea behind you, it will be your first and last time of doing so! Just be sensible with them and they work extremely well.