If a magnet sticks to it, it's ferrous.
I'd like to give a more elaborate answer, but there isn't anything more to it.
That price is absolutely ridiculous, and there is no way the frying pans are worth it. To Americans: that's $250 for 2 frying pans! Even All-Clad retails for $100 for a frying pan, and it is among the most expensive cookware. Now, in this case, many people can justify that price for All-Clad, because they heat fast and evenly and will last for several lifetimes with proper care.
While the Fissler pans may be well-made, I would have a very hard time justifying that kind of money. In particular, the Protect model is nonstick, and nonstick surfaces wear out. There is no way around this. The better ones will last longer, but still you get a couple years of good use before the surface degrades. You're far better off buying a series of cheap restaurant-supply nonstick pans, and replacing them regularly. I can find decent ones for about $20-25, which means you can get one for probably €20. See my answer to What is a good brand for teflon pans? for where to get the best value... and why you shouldn't be spending big money on teflon-coated stuff.
I do not feel the "crispy" model is a safe buy, because it emphasizes a gimmicky crisping surface over versatile everyday use. It also does not describe what, if any, sort of copper/aluminum core it uses to ensure fast, even heating. For a pan at this price range, I would expect a multi-ply construction, with aluminum or copper core. To my mind, this does not bespeak money well spent. At a lower price, it might be an entertaining gimmick, but for that much money you will want a solid, versatile all-around pan.
In fact, with good deals, you could fully equip a kitchen with cookware for that price. I have a 7-piece multi-ply set that I'm quite happy with, and it only cost about $160. Throw in a cheap nonstick pan and a cast-iron skillet, and you're set.
Best Answer
There were five dishes mentioned in that post:
Dutch pancake puffs.
Small, shallow impressions.
Danish pancake balls.
Large, deep (half-spherical) impressions.
Japanese octopus pancake balls.
Small, deep (half-spherical) impressions with a lip around the edge.
Thai coconut pancake snack.
Small, (various depths) impressions
Indian lentil & rice ?balls?.
Deep impressions (various sizes), w/ matching lid.
I have tried my hand at making Kanom Krok in a poffertjes pan, and it came out well. I found that they were a bit too oniony for my taste if I added a pinch of green onion to each side, but it worked out well if I only did it to one of the halves. (don't leave it out, or it's too overwhelmingly sweet). If the indentations had been deeper, there would have been more batter, and thus it might've needed two pinches of onion.
You simply cannot make æbleskiver or takoyaki on anything that isn't half spherical — you're not simply flipping it over (like poffertjes & paddu) or joining two halves together — you need to roll it as you're making it. Æbleskiver can end up with a hollow inside them (that you can fill with apples or such), while takoyaki are often made by flooding the whole pan, and then rolling that extra bit from the top into the sphere so it doesn't have as significant of a void.
You could probably make æbleskiver on a takoyaki pan, but the size difference will mean that you make need a different viscosity and heat to properly set the outside while leaving the inside liquid enough to flow back down to seal the sphere. Takoyaki in an æbleskiver pan might be more difficult — the larger holes might prevent you from cooking the center through properly.
You can use an æbleskiver pan to make poffertjes, but it's a pain. Basically, you just put a little bit in the bottom of each one, and then flip it. You'll still get the right sized puff, because the æbleskiver indentations are much larger (typically 7 per pan vs. 19 for roughly the same diameter). Not only would it be slower from having less indentations, but it's much harder to get in there to flip. It'd be like using a Dutch oven to make an omelette — it might technically work, but it's really not the right tool for the job.
If you really had to, it'd almost be easier to make poffertjes on a griddle — just use a squeeze bottle so that you can more easily control the size of the puffs. It'll be a bit different, but it's better than only making 7 per batch.
I wouldn't make poffertjes on a takoyaki pan — you'd have to make really, really tiny ones, or you'd have to fill it so far that I'd have concerns about the middle cooking properly.
As for the paddu — I've never made it, but it seems to me that it could likely be done it any of the deeper indentation pans, provided you had a good way to cover it to let it steam. It's quite likely that a poffertjes pan would make for too thin of paddu, as you wouldn't get the expected contrast between interior & crust.
So, to summarize (partially assumptions):