SeaKeeper vs Naid At Rest Stabilization

No, they are not. Sleipner's fins are patented, and of course they claim that they are more effective.
But I've yet to see one single independent comparison proving that for any given installation there is a meaningful difference between straight and curved fins.

The simple truth is that fins are the most effective way of stabilizing roll, and it doesn't really matter whether they are straight or curved - it's mostly a matter of having a sophisticated control unit capable to consider all crucial parameters, elaborate in real time the optimal fins movements, and drive some powerful and fast actuators. Btw, that's mostly relevant when operating at zero speed, because under way, the 30 years old gyroscope-based Naiads, with zero electronics and obviously straight and very basic fins, which I enjoyed for 17 years on my old timber trawler, were impressive also by modern standards.
Besides, leaving aside what a source that I consider highly reputable confirmed me in this respect, I had a chance to try, on top of the previous CMC fins, also most others: Sleipner, ABT, Wesmar (not Humphree, though - not yet, anyway, but I can't see how they could be any better).
And all of them, bar none, are amazingly good at their job.

So, IMHO it's impossible to go wrong with fins, it's just a matter of having them sized and installed properly.
Which is a given when fitted by the builder (though also among builders some are better than others), but it can be tricky when retrofitting, particularly on boat models where fins were never factory installed - as is the case of the previous Canados and also of JustAzimut's boat.

Regardless, the key reason why imho electric fins are a no brainer when retrofitting is the MUCH easier installation, with a lot less critical components.
Which eventually also means higher reliability and overall lower costs, though never trivial, obviously.

Well, the video I previously linked was at zero speed, with the engines off and the boat drifting into a long and gentle swell.
And I witnessed that same CMC installation working very well in even worse conditions, including irregular navigation wakes.
But also ABT fins, which I tried on very different boats (S/skr 80 Yacht and Outer Reef 700, both factory installed), never failed to impress me, both under way and at anchor.

The way I see it, I would put it this way: in a scale from 1 to 10, where 1 is a non-stabilized boat and 10 is a boat on the hard, any half decent fin stabilizers, properly sized and installed, deserves an 8, if not 9.
So, trying do determine scientifically if one system is 8.4 and another is 8.7, aside from being almost impossible, is totally irrelevant in practice.
Hence my suggestion, particularly for refit, to follow the easier and less expensive route.
But only as long as the installers aren't at their first rodeo!

C'mon, you know even better than myself two things:
Firstly, sea state always appears in video smoother than it is.
Secondly, adrift boats tend to settle against beam sea - which is precisely what we wanted, in that occasion.

If you think that the Canados 70S, back in her days, earned the status of one of the best and most iconic boats in that size bracket by being a mess, well, think again. Or maybe you're just too young... Which is good for you, of course.

Point taken.
Still, you've yet to read from myself a post where I label a boat I've never seen - let alone sea trialed - "a mess".

Think what you like, but you are judging by the video, while I was actually onboard when I made it.
And we were drifting in an old residual swell from previous days of bad weather, with no fresh wind.
That's what makes the sea surface blurred and not confused/rough at all.
But there were a few other, also larger, boats around us. And they were visibly pitching while heading offshore, with the very same swell on their nose.
And leaving aside the fact that the motion of any boat doesn't depend just on wave height, but also on their length and period, I hope I don't need to explain you that what it takes to make a boat roll is just a fraction of the sea motion, compared to pitching.

That said, the boats comparison is totally O/T in this thread, but hey, you got me started...
Now, as it happens, while you've not even seen any Canados, I have actually been onboard a couple of Hatteras MYs, which in fact around here are more popular than their SFs.
So, let me ask you this: can you think of any other MY where fin stabs are more popular than on Hatteras?
It's not a rethorical question, mind. I've always been puzzled by that, because one should think that neither the builder nor most owners agree with your statement about their roll resistance.

Me, the very little that I know for sure is that even my old round bilge full displacement 53' trawler was MUCH less prone to roll than the Hatt 53 MY of a boating mate, when we were both cruising in tandem at the same speed with centered fins.
The other occasion when I tried a Hatt MY with fin stabs was on a 70', but when I asked the owner to center them and check out the difference, he point blank refused, arguing that he didn't want to scare anyone onboard - go figure.
But of course, the 75' that you mentioned might be different...

Fine, why don't you share them with us?

You can just add @yahoo.com to my username.
But in the context of this thread, wouldn't it be more interesting to just post a link here?
It can't be classified material, if you're willing to share it with me...

I got your three clips, thanks.
But I struggle to understand in which way they can compare with the one I previously posted.
I can upload and link them, possibly removing the two chaps visible in IMG_1771.MOV, if you wish.
Just because otherwise it would be impossible for anyone else to understand/contribute.
Your call, anyway.

PS: I also had a look at the channel you mentioned and you're right, some really nice stuff there.
Being public domain, I assume you don't mind if I add this link for the convenience of anyone else willing to check it out.
Not that there's anything relevant to the topic of this thread, but I'm never shy of going a bit o/t in favour of some nice clips that convey what boating is all about!