Hi Mark
Have used trim tabs on a couple of boats now and found them very worthwhile. Have Lencos now, electric with no hydraulics which is very good as no leaks an easier to instal.
Even when they are not engaged ie down, they are useful as they lengthen the boat. I have not had line cut when fishing so don't findthat an issue either.
Have, in the past, even had the old hydraulic hand pump up style ones and they were still good tho hydraulic oil leaks in the boat is not kool.
Use tabs to keep the boat level esp useful into a head sea to keep the shoulder from banging ie softer ride also helps to lift the boat bum whch allows the full boat length to "work"
Check out Capt Seaweed thread too it has pics of the set up on the Vag which IMHO has improved an already good boat esp in head seas etc
Cheers
Chimo