Yes, tangent normals appear to be working just fine.
no, they don't
Example, posted by mdavies works ok ONLY if hirez is smaller than low rez. But as soon as they have intersections - this intersection areas always rendered as black in C channel and inverted (in some very strange way) in Nt channel. Other channels like occlusion and curvature looks cut there.
In real life situation low poly geometry almost always have intersections (like was shown here
https://vimeo.com/143618200) [
vimeo.com] - so bake tool is still broken unfortunately.
It worked in h15 - all except displacement - it had problems with negative values though.
But it is very promising, waiting when sidefx will fix these.