You do not see as many, but the people I have talked to who have Humphree brand of interceptor trim tabs like them a lot. You see them on some high end sportfishing boats. Up front cost is quite a bit more, but they look to be a better built unit. Larger drive motors situated inside hull against the transom. I also think that they were saying a big problem with these type of tabs is growth that accumulates and eventually breaks them. I think the Humphree has a timer which cycles the trim tab every so often when not using to scrape any growth away that may start to accumulate. A few years back I was talking to the manager of a big marina and he said he has a big pile out back of the Volvo trim tabs that were not working or defective.Many of them are using Zipwakes now. Mixed reviews as to reliability - longevity.