Whale Tail, What's Your Thoughts?

I have a Ranger 190VS fish and ski with a 200hp Optimax, when I bought it no whale tail. After my first trip to the lake I installed a whale tail and will not be caught without one from now on. Cavitation and porpoising is no issue with proper trim whereas before it was a problem regardless how outboard was trimmed. So yes I would say they are a huge benefit regardless of prop pitch.
I ran one on my 82 115hp merc. for 15yrs no issues with stress or strain on the boat or motor. When I traded up to a 95 150hp Johnson I put one on that boat as well and ran it for 17yrs with no issues with stress or strain on the boat or motor.

Cons, you lose one or two mph top end.

Pros, 1 boat planes guicker and at a lower speed.
2 greatly reduces chine walking as well as porpoising.
3 dramatically improved handling and stability in rough water and crossing wakes.

I'm considering putting one on my 16 250hp etec to help with stability and slower planing speed.
A 4 blade prop will also help with quicker planing and at a lower speed, something else I'm considering.
I like the fact that they now offer tails that don't require drilling to install, that was the hard to do on that shiny new skeeter with that shiny new merc. but it was definitely worth it.
if you do any slow speed water sports they will hold you on plane at slower speeds. I used one when kids were younger and did knee boarding and stuff. wow does anyone knee board anymore?
Yuuuuup. Picture of my 2 daughter's this past June double kneeboarding in the Escalante I think just outside of Davis Gulch. They like it, and I don't protest. At least its not tubing! One of them is on an Obrien kneeboard I had growing up 35 years ago. Ok now I feel old.

Back to the OP. This is behind a 22 ft Moomba V-drive inboard running about 15 mph but I have a center trim tab to keep the bow down. But back in the day, again 30 plus years ago, on a 1977 18 ft Bayliner with a 4 cylinder IO we had a whale tail and it made a HUGE difference. We did lose top end speed and like one of the posts said I actually think I remember it cracking part of the aluminum casting on the IO Merc outdrive. Sort of remembering drilling new holes for it and then just kind of leaving it on there.