I for one hate them. I have a 5.4 Traily and havent found a need for one, but have been on a couple of others boats off Dampier and have had a couple of incidents where the foils "grip" especially in a following sea and the sudden pitch IMO isnt fun.

If you need stabilising equipment consider (still IMO dont go) trim tabs. 

 Look into a outboard wedge,angled big of plastic or metal sits under motor mounts.

 Wedges are only used when max trim down ( which should hardly ever be used on a properly trimmed boat) isn't giving enough . A foil is very useful on some boats for making the trim less critical, ie, removing the need for constant trim adjustments. A very good example is the UB Yamaha "banana boats" great hulls, but the narrow beam makes them very sensitive to weight aft and they can struggle to get quickly on the plane, needing to be full in then adjust up when you are up. PITA, should't have to do that with any boat, IMO. I fitted a foil to mine, problem solved with NO adverse affects. YMMV.  I suspect a lot of the crap thrown at foils comes back to operator error--someone fucks up running too fast downwind and blames it on the foil. And, a lot of boats simply dont need them.

I agree with all your comments especially the "operator error". And yes wedge vs h.foil are 2 different species.
I have used them consistently and have never had a problem. I only have good feedback regarding hydrofoils. I cannot comment on one on a particular hull though, only my own personal experience.

My understanding is they will lift the back of the boat up. This lets you plane quicker and hold a plane at a lower speed. However lifting the back of the boat up also angles the front of the boat down at the same time. So if your boat is already a bit bow heavy then it's going to cause problems with bow steer or broaching. On the other hand if the boat is rear heavy and you have problems with porpoising it might help by lifting the back up a bit.

They claim that you can save a bit of fuel by planing at a lower speed but you also increase the drag through the water so I don't know if you really end up better off.

I wouldn't put one on your boat unless you have a problem with the bow riding too high.

IMO they are an absolute last resort in an attempt to fix a problem that can be sorted in other ways
They create lift on the stern of the boat and inmost cases its when the last thing you need, like in a following sea and all of a sudden you find yourself broaching because the arse end has lifted

 I have a 5.3 traily and l certainly wouldnt be putting one on. The weights already up front with the forward driving position . Also as stated these hulls arent the greatest in a following sea and have a tendency to broach.

thanks for the feedback guys, looks like i won't be putting one on

 If your boat was bow heavy in the first place, why on earth would you fit one?  I suspect some are sold because inexperienced operators think it will just make their boat " better" in terms of speed, fuel consumption, or some unspecified benefit. On the right combination, very useful with no negative effects. And, as some others have said, they can perhaps have a negative effect--apart, that is, from the obvious one of drilling holes in your cav plate and letting corrosion start. Horses for courses, you need to look at each case and not condemn them outright/praise them to the skies as a blanket reaction.

 All good, they are a lot heavier in the aft, tho being a runabout while moving all the weight is up front.

i generally haven't had any dramas with how the boat handles. I was just seeing if anyone had the same boat with one and the pros and cons. 

But I think I'll leave it off. Cheers again 

i have had several traillys and for a forward control boat I would avoid putting on a foil , the boats I had where all centre consoles and I trialled the foils and found on those rigs there were good times and bad , I had the best improve,net by moving the fuel tank forward  600 mm and made a big difference  . 

 I have a 5.3 trailcraft and it's a bit under powered with only a 75 hp four stroke

It Has had a hydrofoil fitted to it since I purchased the boat second hand so I don't know how it went without it but I take her out in some very rough seas and a long way out and never had any issues but I just drive to the conditions 

I have always presumed it was fitted because it was under powered and helped it get on the plane easier