What is the general concensus of these new 'super magnets' as they apply to model railroad, HO that is, operation. I've been an N gauger for 40 years but the eyes aren't what they once were and I'm switching to HO and building a small pike.
They work great if you pick the right ones and mount them properly. I've done quite a bit of experimentation with the different types, sizes and mounting options. Some like to embed small cylindrical ones in the roadbed alongside the track, but I've found that the ones that work best are 1/8"x1/8"x1/2" rectangular magnets, with polarity along the 1/2" length. They fit nicely in between the ties, and can be made flush with the ties if you make a small indent in the roadbed. Glue two or three of them in adjacent inter-tie gaps, and that should give you just about the right combination of length & strength for delayed uncoupling of just about anything. At a few dozen cents a pop, they're a hell of a lot cheaper than any other option out there.
I've been using craft magnets for years to make uncoupling ramps on S scale SHABBONA RR. I slide a piece of magnetic metal under the track and mount them on that, to prevent them from rising and snagging rolling stock passing over them. They work well, and I can use regular HO Kadee #5 style couplers. If I get one that's a little sticky, I increase the radius of the uncoupling pin with a pair of pliers.
Model Railroader magazine