Experiences with FLIR cams?

Like everything else it depends on how you use the boat. If you run at night a lot, and if you run from an enclosed PH yes it is very useful.

but to make the most of it, you really need it on a fairly large screen.

on the 84 skylounge I run, I have the FLIR output going to a full size monitor. During the day I use it for on board video camera and switch input to FLIR when I need to use it. In my opinion FLIR on a small MFD or worst on a split screen MFD is pretty useless

It's VERY useful if it comes with a boat that you are buying, because after selling it on eBay you can use the money for something much more worth, like restocking your wine cellar.
And depending on the exact model, you might even throw in some bottles of Cristal Roederer!

PS: I'm saying this based on a first hand experience of being on watch at night, together with the boat owner who was keeping his eyes on the FLIR screen almost constantly, while helming the boat.
And when we were on a collision course with a stand-on vessel whose red and white I clearly saw approaching on our stbd side with Mk1 eyeball, I had to warn him about that, because it was just outside the camera FoV and he saw nothing at all.

Not really. In my example, the night was crystal clear, and in such conditions radar only comes second, after eyeball.
Depending on sea conditions, a very small boat can be missed by the radar (been there), even if its navlights can still be easily spotted.
In fog or any other low-vis conditions, then yes of course, radar becomes the primary tool.

That said, I agree that in completely dark anchorages or a MOB situation, a thermal camera has its purpose.
But not while cruising, where I wouldn't even bother turning it on if I had it on my boat.
Overrated is the first adjective that springs to mind with FLIR, imho.

PS: On the other hand, I wouldn't mind a tool like the Caterpillar S62 for checking all sort of onboard systems - in fact, I'm considering to get one - but that's a totally different kettle of fish, of course.

Again it depends on the boat. Open helm yes it s a gadget. Not needed. Enclosed pilothouse, yes.

If anything it eliminates the need to use a spotlight to spot day markers, something which is at the very least rude to folks coming the other way. I also find that messing with a spotlight joystick to be a lot more distracting. Our home marina as a fairly long and narrow channel with only 2 lit markers out of a dozen. I almost never have to use the spotlights. Yea the radar helps heading in the right direction but once within a couple of hundred meters the FLIR is very useful. Again, when in an enclosed PH

same in some of the unmarked narrow cuts in the Bahamas. I often come in Cat Cay cut at night and the FLIR makes it a lot easier when making the 90 degree turn along the tip of Gun Cay

but like everything, it s a tool but not the only tool to use. Plotter and radar and most importantly the good ole fashion eye ball

Well, maybe. By definition, I am unaware of what I don't know - I'm not different from any other other human being in this respect!
And overrated or not is to a large extent a matter of personal viewpoint (and wealth!), anyway.
I would call also the stuff that Roederer put in their bottles overrated, FWIW.

But as long as you agree that it's pointless for "normal cruising" conditions, we aren't too far away, I reckon.
Essentially, my point - as also the OP said, BTW - is that I never missed the thing, in the overwhelming majority of days of boating spent without it vs. just some spent with it. And I can't think of one single case in decades of boating, inclusive of both night cruising and anchoring, where I felt limited by not having a thermal camera.
Each to their own, though.

PS: nice to read that Pascal shares my view on eyeball relevance.

I have it on the 84 Lazzara i run and being a skylounge it s a very useful tool as explained above.

I don’t have one on my 53 and not even considering it since i always run from the open FB. Not needed. My old eyeballs work just fine

i m not sure a log would be visible on these recreational FLIR unless it is dead calm and glassy

Here are a few real world shots I took tonight.

first one is at the dock. The spoil island is about 100/120 yards away

second one is approaching the entrance to Miami Beach marina, breakwaters are showing very well which is good since the lights are out

Last two.

first one was taken 1/4 mile (measured by radar) from the two day markers

second one shows a marker at close range and a sunken mast less sailboat tied to it

note that under certain conditions, hot humid muggy nights, visibility and contrast can be less than half of what it was tonight

Again that s on a full size monitor. Put the image on a smaller screen and these day markers at 1/4 mile will not be visible